First Report of an Iridophoroma in a Tegu (Salvator merianae)

First Report of an Iridophoroma in a Tegu (Salvator merianae) | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Case Report First Report of an Iridophoroma in a Tegu (Salvator merianae) Sorana CATOI, Romelia POP, Lucia-Victoria BEL, Iulia MELEGA, Alexandru-Flaviu TABARAN This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7029183/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 26 Feb, 2026 Read the published version in BMC Veterinary Research → Version 1 posted 11 You are reading this latest preprint version Abstract Background: This case report describes the clinical and histological findings of a rare ocular iridophoroma in a tegu. Case presentation: Iridophoroma is a rare type of chromatophoroma, a tumor that arises from iridophores, specialized pigment cells responsible for reflecting light. This case report describes a 6-year-old male Argentine black and white tegu ( Salvator merianae ) presented with a large, irregular, proliferative mass in the periocular region. The mass originated from the upper left eyelid, partially obstructing the ocular surface, and measured 2.5 cm in diameter. The patient was referred to the department of Surgery and Intensive care for mass removal and underwent two separate surgical resections. Fine needle aspiration from the structure revealed the diagnosis of iridophoroma, which was later confirmed through histology. This case aims to broaden current knowledge in reptile medicine by presenting an iridophoroma in Salvator merianae , highlighting its clinical presentation, cytological features, and histopathological aspects. Conclusions: This case represents the first documented occurrence of an iridophoroma in a tegu, highlighting the need for increased awareness and precision in diagnosing tumors in reptiles. The findings demonsrate the importance of paraclinical investigations, such as histopathology, not only in confirming rare conditions but also in differentiating iridophoromas from other potential diagnoses, such as squamous cell carcinoma, papilloma, or melanophoroma. Accurate identification is crucial for guiding appropriate treatment and improving outcomes in reptile medicine. Iridophoroma Tegu (Salvator merianae) Reptile tumor Ocular neoplasia Figures Figure 1 Figure 2 Background Cromatophoromas are rare neoplasms composed of pigment-producing and light-reflecting cells that affect the skin of reptiles, fish, and amphibians [1,2], (Table 1). These neoplasms are categorized based on the type of pigment they contain. Typically, chromatophoromas originate in the skin of the head and body, with reported sizes ranging from 0.2 to 2.0 cm in diameter. Chromatophoromas are neuroectodermal tumors that typically appear as raised, pigmented masses and are most commonly reported in snakes, followed by lizards, chelonians, and crocodilians [3,4]. Reptilian skin contains three primary types of pigment cells, collectively known as chromatophores. Tumors arising from these cells are classified into distinct subtypes depending on their pigment composition: melanophoromas, also referred to as melanomas, which involve melanin-producing cells, xanthophoromas, derived from cells responsible for producing carotenoid or pteridine pigments, and iridophoromas, which develop from crystalline purine-containing cells that house reflective granules of guanine, adenine, hypoxanthine, or uric acid [5]. Cutaneous neoplasms have been documented across various reptilian orders, with many cases linked to improper conditions in captivity. Factors such as excessive humidity, prolonged exposure to solar radiation, and unsuitable enclosures contribute to the development of these tumors [6]. Case presentation Clinical examination: A 6-year-old male tegu weighing 5 kilograms was referred to the Department of Surgery and Intensive Care for evaluation of a mass on the superior left eyelid, which had progressively increased in size over the course of one year. On examination, the mass measured approximately 2.5 cm in diameter and had a firm, non-mobile, and non-painful consistency upon palpation (Fig. 1 a). Given the lesion’s progressive growth, and following a general consultation, the owner consented for excisional surgery. The anesthetic protocol included premedication with medetomidine (0.1 mg/kg) and ketamine (10 mg/kg). Analgesia was provided using morphine at a dose of 5 mg/kg. Anesthesia was induced and maintained with isoflurane, and mechanical ventilation was provided throughout the procedure. Additionally, local infiltration with 2% lidocaine (2 mg/kg) was administered for regional anesthesia. The lizard was positioned in sternal recumbency, and the ocular and periocular regions were surgically prepared using diluted povidone-iodine and a transparent surgical drape. The mass was excised using a curvilinear incision extending from the medial canthus along the upper eyelid to the lateral eyelid junction. Sharp dissection was used to separate the mass from adjacent tissues. Bipolar cautery was applied for hemostasis, and the surgical site was irrigated with sterile saline. Both the subcutaneous tissue and the skin were closed using 4 − 0 monofilament absorbable suture in an everted pattern (Fig. 1 b). The patient’s recovery from surgery and anesthesia was uneventful. Postoperative pain management included morphine administered at a dose of 5 mg/kg every 12 hours for five days, and meloxicam at a dose of 0.5 mg/kg once daily for ten days. Local antibiotic therapy with kanamycin was used, along with systemic ceftazidime at 20 mg/kg every 48 hours, for a total of ten doses. Following the first surgery, the mass recurred rapidly, increasing in size to approximately 5 cm within 1.5 months (Fig. 1 c). Given the rapid regrowth of the lesion, the owner consented to a second surgical procedure. This second surgery involved enucleation of the affected eye and was performed using the same anesthetic protocol as the initial operation (Fig. 1 d). Postoperative treatment remained unchanged. Two months after the second surgery, the mass recurred, this time invading the surrounding tissues so extensively that another surgical procedure was no longer possible. Due to the poor prognosis, rapid time of recurrence and the fact that the quality of life of the animal was affected (was not eating properly, was very lethargic and long term management with nonsteroidal anti inflammatory medication was not effective), the patient, under general anesthesia with 0.2 mg/kg medetomidine and 20 mg/kg ketamine, was euthanized using intracardiac administration of pentobarbital 1 mg/kg. Once lack of corneal reflex was confirmed, pithing was performed. Following euthanasia, the body was submitted to the Pathology Department at the University of Agricultural Sciences and Veterinary Medicine in Cluj-Napoca, Romania, for further investigation. The lizard was submitted for necropsy due to a progressively enlarging ocular mass. A well-demarcated, irregular, multilobulated mass measuring up to 2.5 cm in diameter was identified at the medial canthus of the left eye. The mass was firm yet slightly compressible, with a predominantly white to pale pink coloration. Its surface was irregular and finely granular in appearance. The mass exerted pressure on the ocular globe, causing visible indentation and mild displacement of the eye within the orbit. The surrounding eyelid was thickened and distorted, exhibiting an irregular contour due to the mass effect. Additionally, mild conjunctival hyperemia and a serous to mucoid ocular discharge were noted, likely secondary to chronic irritation and impaired tear drainage. No evidence of metastasis or other significant pathological findings was observed in the remaining organs during necropsy. For cytology, several imprint smears were prepared and routinely stained using a Diff-Quik staining kit. The prepared slides were then analyzed using an Olympus BX51 microscope, and bright-field images were captured with an Olympus SP350 digital camera. Image processing was performed using the Olympus cellSens software. The slides were well-cellularized, with a well-preserved cellular population. The cells were round to oval in shape, with indistinct borders and abundant, finely granular cytoplasm. The neoplastic cells exhibited a single large nucleus with 1–2 prominent nucleoli (Fig. 2 a, b). The background was moderately proteinaceous. Anisocytosis and anisokaryosis were moderate. Polarized light was used to enhance the visualization of cytoplasmic granules (Fig. 2 c). For histological examination, the ocular mass was preserved in 10% neutral buffered formalin (NBF) and subsequently embedded in paraffin, following a standard tissue processing protocol. Thin sections, measuring 2 micrometers, were stained with hematoxylin and eosin (H&E). The histopathological exam showed a well-demarcated mass composed of a dense proliferation of pigmented cells arranged in sheets and nests within a well-vascularized stroma. The neoplastic cells exhibit abundant cytoplasm containing iridescent, reflective pigment granules, characteristic of iridophores. The nuclei are round to oval with finely dispersed chromatin and occasional prominent nucleoli. Mild to moderate anisocytosis and anisokaryosis may be observed, with rare mitotic figures (Fig. 2 d, e). The tumoral mass focally infiltrates the adjiacent tissue. Under polarized light, the neoplastic iridophores display bright, refractile cytoplasmic granules with a metallic or crystalline appearance, enhancing their identification within the tumor mass (Fig. 2 f). Discussion Color changes in reptiles result from the response of dermal chromatophores to nervous and/or endocrine stimulation [7]. The integrated nature of responses of xanthophores, iridophores, and melanophores, which together constitute the dermal chromatophore unit, provides the means for the rapid color change of amphibians in response to hormonal stimulation [8]. An understanding of the fundamental morphological characteristics of reptilian skin is essential for recognizing and interpreting pathological changes. The integument of reptiles is composed of the epidermis and the dermis. The epidermis consists of three layers. The inner layer is called the stratum germination, which contains cuboidal cells that produce keratin in two forms: alpha-keratin, which is flexible and located between the scales, and beta-keratin, which provides strength and hardness. In addition, it has an intermediate layer with a water-proving barrier, containing a membrane rich in lipids, and the outermost layer, the stratum corneum, is highly keratinized, where scales are formed [2, 9]. The dermis contains a conjunctival portion that comes from the underlying mesoderm, rich in collagen, blood vessels, sensory receptors, nerves, fibroblasts, histiocytes, plasma cells, reticulocytes, and chromatophores, obtaining a primary function of nourishing the epidermis and adhering to the skin. musculature through connective tissue. Most reports of skin tumors in reptiles are based on individual case studies and primarily include squamous cell carcinomas (SCCs), papillomas, and chromatophoromas. [8]. The diagnosis of neoplasms in reptiles can often be difficult to establish during the initial evaluation due to the nonspecific nature of the associated clinical signs [10]. Reports of skin tumors in reptiles are largely derived from single cases and mainly comprise squamous cell carcinomas (SCCs), papillomas, and chromatophoromas [6]. The main differential diagnoses include squamous cell carcinoma, papiloma, and melanophoroma. Cutaneous neoplasms in reptiles are commonly reported as isolated cases; among current reports, squamous cell carcinoma stands out as the most common, followed by papilloma and chromatophoromas [11]. Histopathology and cytology are essential for differentiating between iridophoromas, melanophoromas, squamous cell carcinomas (SCCs), and papillomas in reptiles. Iridophoromas contain guanine platelets arranged in reflective stacks, exhibit birefringence under polarized light, and lack melanin pigmentation. In contrast, melanophoromas are heavily pigmented due to melanosomes, which stain positively with Fontana-Masson and display cellular pleomorphism, anisocytosis, and anisokaryosis [3,5,12]. SCCs, among the most frequently diagnosed neoplasms in reptiles, exhibit epidermal hyperplasia, keratinocyte dysplasia, karyomegaly, nuclear hyperchromatism, and mitotic figures in basal and suprabasal keratinocytes, with a loss of polarity in affected cells [13,14]. Papillomas, in contrast, are benign epithelial tumors associated with papillomavirus infections, characterized by basal cell hyperplasia, acanthosis, hyperkeratosis, and intranuclear inclusion bodies. Unlike papillomas, iridophoromas lack papillary architecture and keratinization, remaining confined to the dermis [15]. These histopathological differences are crucial for accurate diagnosis and appropriate treatment selection. While chromatophoromas typically originate in the skin of the head and body [3,4], they have also been reported in other anatomical locations, indicating a wider potential for distribution (Table 1.). Table 1. Documented Cases of Chromatophoromas in reptiles and fish: Breed, Age, Tumour type and Localisation N o Breed Age (years) Tumour Type Localization References 1. Green iguana ( Iguana iguana ) 11 Iridophoroma Periocular mass [16] 2. Savannah monitor ( Varanus exanthematicus ) 13 Malignant Non-Pigmented Chromatophoroma Oral [17] 3. Veiled chameleon ( Chamaeleo calyptratus ) 6 Mixed Chromatophoroma with Cutaneous, Pulmonary, and Testicular Metastases Right mandible [18] 4. Bearded dragon ( Pogona vitticeps ) Adult Malignant chromatophoroma Left caudal aspect of the cranium [4] 5. Day Gecko ( Phelsuma madagarescencis grandis ) 11 Malignant chromatophoroma Outer distal portion of the right thigh [19] 6. Siamese fighting fish ( Betta splendens) NS Mixed chromatophoroma (benign irido-melanocytoma) Base of the caudal peduncle [20] 7. Siamese fighting fish ( Betta splendens ) NS Chromatophoroma Right eye [21] 8. Crevice kelpfish ( Gibbonsia montereyensis) NS Chromatophoroma Right side of the head [9] 9. Largemouth bass ( Micropterus salmoides ) NS Chromatophoroma Ventrocaudal to the right eye [22] 10. Betta fish ( Betta splendens ) NS Uveal iridophoroma Intraocular [23] 11. Shubunkin goldfish 9 NS Cornea [24] 12. Eastern yellowbelly racer (Columber constrictor flaviventris) Subadult Multiple Chromatophoromas The dorsal and right epaxial musculature [25] NS, not specified. Conclusion This is the first documented case of iridophoroma in a tegu ( Salvator merianae ), emphasizing the need for greater awareness and precision in reptile tumor diagnosis. Early surgical intervention with wide margins is recommended to prevent recurrence. The findings highlight the importance of paraclinical investigations in confirming rare conditions and distinguishing iridophoromas from squamous cell carcinoma, papilloma, or melanophoroma. Accurate diagnosis is essential for guiding treatment and improving outcomes in reptile medicine Abbreviations NS, not specified. SCC, squamous cell carcinoma. NBF, neutral buffered formalin. Declarations Acknowledgements Not applicable Author contributions SC: Conceptualization, Data curation, Writing – original draft. RP: Writing – review & editing. L-VB: Writing – review & editing. IM: review & editing. A-FT: Investigation, Writing – review & editing. Funding The author(s) declare that financial support was received for the research, authorship, and/or publication of this article. The University of Agriculture Science and Veterinary Medicine Cluj-Napoca, Romania. Data availability The original contributions presented in the study are included in the article/supplementary material; further inquiries can be directed to the corresponding author. Ethics approval and consent to participate The animal studies were approved by the University Ethics Committee and the Bioethics Subcommittee for Experiments on Animals, Plants, or Human Subjects. University of Agriculture Science and Veterinary Medicine Cluj-Napoca, Romania. The studies were conducted by the local legislation and institutional requirements. Written informed consent was obtained from the owners for the participation of their animals in this study. Consent for publication Written informed consent was obtained from the owner of the tegu for the publication of the case report. Competing interests The authors declare no competing interests. References Diniz SLP, Oliveira Filho HS, Santos KM, Duarte JLC, Oliveira RL, Pierezan F, et al. Gross, histologic, and ultrastructural features of iridophoromas in Siamese fighting fish (Betta splendens). Vet Pathol. 2024. https://doi.org/10.1177/03009858241281887 Guo L, Bloom J, Sykes S, Huang E, Kashif Z, Pham E, et al. Genetics of white color and iridophoroma in “Lemon Frost” leopard geckos. PLoS Genet. 2021;17(6). https://doi.org/10.1371/journal.pgen.1009580 Silva S, de Freitas LR, Pereira LP, da Silva MEM, Chinen KH, Bandarra MB. First report of melanophoroma in Salvator merianae. Braz J Vet Pathol. 2024;17(2):104–7. Strunk A, Haney S, Reavill D. Malignant chromatophoroma in a bearded dragon (Pogona vitticeps). In: Proc Assoc Rept Amphib Vet. 2009;73–6. Heckers KO, Aupperle H, Schmidt V, Pees M. Melanophoromas and iridophoromas in reptiles. J Comp Pathol. 2012;146(2–3):258–68. https://doi.org/10.1016/j.jcpa.2011.07.003 Garner MM, Hernandez-Divers SM, Raymond JT. Reptile neoplasia: a retrospective study of case submissions to a specialty diagnostic service. Vet Clin North Am Exot Anim Pract. 2004;7(3):653–71. https://doi.org/10.1016/j.cvex.2004.04.002 Parker GH. Animal colour changes and their neurohumours: a survey of investigations 1910–1943. Cambridge: Cambridge University Press; 2012. https://books.google.com/books?id=8OKAEmARDIoC Sykes JM IV, Trupkiewicz JG. Reptile neoplasia at the Philadelphia Zoological Garden, 1901–2002. J Zoo Wildl Med. 2006;37(1):11–9. https://doi.org/10.1638/04-112.1 Camus MS, Hyatt MW, Clauss TM, Berliner AL, Camus AC. Chromatophoroma in a crevice kelpfish (Gibbonsia montereyensis). Vet Clin Pathol. 2011;40(4):549–52. https://doi.org/10.1111/j.1939-165X.2011.00365.x Taylor JD, Hadley ME. Chromatophores and color change in the lizard, Anolis carolinensis. Z Zellforsch. 1970;104. Kubiak M, Denk D, Stidworthy MF. Retrospective review of neoplasms of captive lizards in the United Kingdom. Vet Rec. 2020;186(1):28. https://doi.org/10.1136/vr.105308 de Freitas SSLR, de Paula Pereira L, da Silva MEM, Chinen KH, Bandarra MB. First report of melanophoroma in Salvator merianae. Braz J Vet Pathol. 2024;17(2):104–7. https://doi.org/10.24070/bjvp.1983-0246.v17i2p104-107 Solanes Vilanova F, Hellebuyck T, Chiers K. Histological variants of squamous and basal cell carcinoma in squamates and chelonians: a comprehensive classification. Animals (Basel). 2023;13(8). https://doi.org/10.3390/ani13081327 Solanes-Vilanova F, Chiers K, Gil-Lianes J, Hellebuyck T. Clinical features, surgical management and outcome of squamous and basal cell carcinoma in squamates and chelonians. Vet Dermatol. 2024;35(6):626–40. https://doi.org/10.1111/vde.13282 Meuten DJ. Tumors in domestic animals. 5th ed. Ames: Wiley-Blackwell; 2017. Rousselet E, de Mello Souza CH, Wellehan JFX, Epperson ED, Dark MJ, Wamsley HL. Cutaneous iridophoroma in a green iguana (Iguana iguana). Vet Clin Pathol. 2017;46(4):625–8. https://doi.org/10.1111/vcp.12536 Durska M, Mikiewicz M, Paździor-Czapula K, Gesek M, Otrocka-Domagała I. Histopathological and immunohistochemical evaluation of malignant non-pigmented chromatophoroma in a savannah monitor (Varanus exanthematicus) – a case study. 2024. https://doi.org/10.2139/ssrn.4885623 Lewis N, Martinson S, Wadowska D, Desmarchelier M. Malignant mixed chromatophoroma with cutaneous, pulmonary, and testicular metastases in a veiled chameleon (Chamaeleo calyptratus). J Herpetol Med Surg. 2015;25(1–2):16. https://doi.org/10.5818/1529-9651-25.1.16 Mikaelian I, Lynch S, Harshbarger JC, Reavill DR. Malignant chromatophoroma in a day gecko (Phelsuma madagascariensis grandis). 2007. Shivley JM, Brookshire WC, Baumgartner WA. Mixed chromatophoroma (benign irido-melanocytoma) in a male Siamese fighting fish, Betta splendens, Regan. J Fish Dis. 2021;44(3):351–4. https://doi.org/10.1111/jfd.13303 Ciambrone C, Chen LR, Tokarz DA, Lewbart GA. Chromatophoroma in a Siamese fighting fish (Betta splendens). Vet Rec Case Rep. 2019;7(2):e000840. https://doi.org/10.1136/vetreccr-2019-000840 Yaw TJ, Michaels B, Reavill D, Zaffarano BA. Liquid nitrogen cryosurgery for a chromatophoroma in a captive largemouth bass (Micropterus salmoides). J Exotic Pet Med. 2016;25(4):305–10. https://doi.org/10.1053/j.jepm.2016.07.001 Crevoiserat L, Katzenstein N, LaDouceur EEB. Uveal iridophoroma in a betta fish (Betta splendens). J Comp Pathol. 2024;215:71–5. https://doi.org/10.1016/j.jcpa.2024.09.006 Kim S, Moore BA, Parker C, Siniard WC, Ang J, Teixeira LBC, et al. Clinical and histopathological features of proliferative corneal lesions in Cyprininae fishes: implications for treatment and insights into corneal tumors. Vet Ophthalmol. 2024;27(3):200–13. https://doi.org/10.1111/vop.13133 Suedmeyer WK, Garner JNB, Franklin AF. Diagnosis and clinical management of multiple chromatophoromas in an eastern yellowbelly racer (Coluber constrictor flaviventris). J Zoo Wildl Med. n.d. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 26 Feb, 2026 Read the published version in BMC Veterinary Research → Version 1 posted Editorial decision: Revision requested 20 Nov, 2025 Reviews received at journal 13 Sep, 2025 Reviewers agreed at journal 23 Aug, 2025 Reviewers agreed at journal 22 Aug, 2025 Reviews received at journal 22 Aug, 2025 Reviewers agreed at journal 21 Aug, 2025 Reviewers invited by journal 21 Aug, 2025 Editor assigned by journal 23 Jul, 2025 Editor invited by journal 23 Jul, 2025 Submission checks completed at journal 21 Jul, 2025 First submitted to journal 21 Jul, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7029183","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Case Report","associatedPublications":[],"authors":[{"id":508084480,"identity":"e374f765-4f0d-4996-9021-d624fdd287e4","order_by":0,"name":"Sorana CATOI","email":"","orcid":"","institution":"University of Agricultural Sciences and Veterinary Medicine of Cluj-Napoca","correspondingAuthor":false,"prefix":"","firstName":"Sorana","middleName":"","lastName":"CATOI","suffix":""},{"id":508084481,"identity":"a6eb38ae-e9d8-4e1d-8298-9182fafc0aa7","order_by":1,"name":"Romelia POP","email":"","orcid":"","institution":"University of Agricultural Sciences and Veterinary Medicine of Cluj-Napoca","correspondingAuthor":false,"prefix":"","firstName":"Romelia","middleName":"","lastName":"POP","suffix":""},{"id":508084484,"identity":"ea81771e-e75e-4e2e-b26a-8a7e3ceed2d7","order_by":2,"name":"Lucia-Victoria BEL","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA40lEQVRIiWNgGAWjYBACAyA+AEJ87A0QET4GhgTitLDxHICIsBGjBayLTSIBroWAwySSHx74wXBHjk3yjfGHnzmH5YF6HzBXVODTkmZwsIfhmTGbdI6ZZO+2w4ZtEgkJjGfO4NOSw3CAh+FwYhtQCwPvtrQENpCWxjb8Wg7+YThc3yZ5xvjjX2K1HAbaAlTJYyDNu82GCC08zwwOyxg8M2zjSSuTlt1mA2Q8SDjYgMcv9u3Jjz++qbgjz89+ePPHt9skgIycxIcNeEIMahcKjyfhACEN6ICdZB2jYBSMglEwvAEAShxMa3F2C/cAAAAASUVORK5CYII=","orcid":"","institution":"University of Agricultural Sciences and Veterinary Medicine of Cluj-Napoca","correspondingAuthor":true,"prefix":"","firstName":"Lucia-Victoria","middleName":"","lastName":"BEL","suffix":""},{"id":508084485,"identity":"93b47a39-1738-4f7b-bbe9-8e19450160e4","order_by":3,"name":"Iulia MELEGA","email":"","orcid":"","institution":"University of Agricultural Sciences and Veterinary Medicine of Cluj-Napoca","correspondingAuthor":false,"prefix":"","firstName":"Iulia","middleName":"","lastName":"MELEGA","suffix":""},{"id":508084486,"identity":"8c939c06-f945-42c1-b725-83c78ae956f5","order_by":4,"name":"Alexandru-Flaviu TABARAN","email":"","orcid":"","institution":"University of Agricultural Sciences and Veterinary Medicine of Cluj-Napoca","correspondingAuthor":false,"prefix":"","firstName":"Alexandru-Flaviu","middleName":"","lastName":"TABARAN","suffix":""}],"badges":[],"createdAt":"2025-07-02 12:08:16","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7029183/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7029183/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s12917-025-05255-0","type":"published","date":"2026-02-26T15:58:37+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":90314968,"identity":"1b35e64e-4f3c-4252-a00e-c599431650a1","added_by":"auto","created_at":"2025-09-01 10:10:49","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":217218,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eClinical progression and surgical management of the iridophoroma in a tegu.\u003c/strong\u003e\u003cbr\u003e\nImage (a): Initial presentation of the periocular mass, located on the upper left eyelid, displaying a firm, irregular, non-ulcerated lesion partially obstructing the eye.\u003cbr\u003e\nImage (b): Postoperative appearance following the first surgical excision, showing reduction of the mass and partial restoration of the eyelid contour.\u003cbr\u003e\nImage (c): Recurrence of the mass two months after the initial intervention, characterized by a larger, more invasive lesion with expansion toward the periocular tissues.\u003cbr\u003e\nImage (d): Intraoperative view during the second surgery, showing extensive tissue involvement requiring enucleation.\u003c/p\u003e","description":"","filename":"1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7029183/v1/5e4cd75d5e28f437c5a30097.jpg"},{"id":90314970,"identity":"24e29e6e-02a5-4aef-8988-9402f67059bb","added_by":"auto","created_at":"2025-09-01 10:10:49","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":242906,"visible":true,"origin":"","legend":"\u003cp\u003eCytological and histological features of iridophoroma. A well-preserved cellular population consisting of round to oval neoplastic cells with abundant granular cytoplasm and large nuclei featuring prominent nucleoli were present. Moderate anisocytosis and anisokaryosis were observed (Image A and B), along with enhanced visualization of cytoplasmic granules under polarized light (Image C). A well-demarcated mass of pigmented iridophore cells arranged in sheets and nests was observed within a vascular stroma. The neoplastic cells showed abundant reflective pigment granules, mild to moderate cellular atypia (Image D and E), and bright refractile granules under polarized light (Image F). Diff-Quik stain (Image A, B and C), H\u0026amp;E stain (Image D, E and F). Ob. x10 (Image D and F), ob. x20 (Image A and C), ob. x40 (Image E), ob. x100 (Image B). Scale Barr 50µm (Image D and F), 20µm (Image A and C), 10µm (Image E), 5µm (Image B).\u003c/p\u003e","description":"","filename":"2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7029183/v1/decba51dcd35b9cac78c0cdd.jpg"},{"id":103765717,"identity":"efe625e8-8990-4085-85e0-f738234ebfcd","added_by":"auto","created_at":"2026-03-02 16:08:08","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":882328,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7029183/v1/b4aca03f-5278-4ccb-82c6-7811b6478122.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"First Report of an Iridophoroma in a Tegu (Salvator merianae)","fulltext":[{"header":"Background","content":"\u003cp\u003eCromatophoromas are rare neoplasms composed of pigment-producing and light-reflecting cells that affect the skin of reptiles, fish, and amphibians [1,2], (Table\u0026nbsp;1). These neoplasms are categorized based on the type of pigment they contain. Typically, chromatophoromas originate in the skin of the head and body, with reported sizes ranging from 0.2 to 2.0 cm in diameter. Chromatophoromas are neuroectodermal tumors that typically appear as raised, pigmented masses and are most commonly reported in snakes, followed by lizards, chelonians, and crocodilians [3,4].\u003c/p\u003e\u003cp\u003eReptilian skin contains three primary types of pigment cells, collectively known as chromatophores. Tumors arising from these cells are classified into distinct subtypes depending on their pigment composition: melanophoromas, also referred to as melanomas, which involve melanin-producing cells, xanthophoromas, derived from cells responsible for producing carotenoid or pteridine pigments, and iridophoromas, which develop from crystalline purine-containing cells that house reflective granules of guanine, adenine, hypoxanthine, or uric acid [5].\u003c/p\u003e\u003cp\u003eCutaneous neoplasms have been documented across various reptilian orders, with many cases linked to improper conditions in captivity. Factors such as excessive humidity, prolonged exposure to solar radiation, and unsuitable enclosures contribute to the development of these tumors [6].\u003c/p\u003e\u003cp\u003e\u003c/p\u003e"},{"header":"Case presentation","content":"\u003cp\u003eClinical examination:\u003c/p\u003e\u003cp\u003eA 6-year-old male tegu weighing 5 kilograms was referred to the Department of Surgery and Intensive Care for evaluation of a mass on the superior left eyelid, which had progressively increased in size over the course of one year. On examination, the mass measured approximately 2.5 cm in diameter and had a firm, non-mobile, and non-painful consistency upon palpation (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea). Given the lesion’s progressive growth, and following a general consultation, the owner consented for excisional surgery.\u003c/p\u003e\u003cp\u003eThe anesthetic protocol included premedication with medetomidine (0.1 mg/kg) and ketamine (10 mg/kg). Analgesia was provided using morphine at a dose of 5 mg/kg. Anesthesia was induced and maintained with isoflurane, and mechanical ventilation was provided throughout the procedure. Additionally, local infiltration with 2% lidocaine (2 mg/kg) was administered for regional anesthesia.\u003c/p\u003e\u003cp\u003eThe lizard was positioned in sternal recumbency, and the ocular and periocular regions were surgically prepared using diluted povidone-iodine and a transparent surgical drape. The mass was excised using a curvilinear incision extending from the medial canthus along the upper eyelid to the lateral eyelid junction. Sharp dissection was used to separate the mass from adjacent tissues. Bipolar cautery was applied for hemostasis, and the surgical site was irrigated with sterile saline. Both the subcutaneous tissue and the skin were closed using 4 − 0 monofilament absorbable suture in an everted pattern (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb).\u003c/p\u003e\u003cp\u003eThe patient’s recovery from surgery and anesthesia was uneventful. Postoperative pain management included morphine administered at a dose of 5 mg/kg every 12 hours for five days, and meloxicam at a dose of 0.5 mg/kg once daily for ten days. Local antibiotic therapy with kanamycin was used, along with systemic ceftazidime at 20 mg/kg every 48 hours, for a total of ten doses.\u003c/p\u003e\u003cp\u003eFollowing the first surgery, the mass recurred rapidly, increasing in size to approximately 5 cm within 1.5 months (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec). Given the rapid regrowth of the lesion, the owner consented to a second surgical procedure. This second surgery involved enucleation of the affected eye and was performed using the same anesthetic protocol as the initial operation (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ed). Postoperative treatment remained unchanged.\u003c/p\u003e\u003cp\u003eTwo months after the second surgery, the mass recurred, this time invading the surrounding tissues so extensively that another surgical procedure was no longer possible. Due to the poor prognosis, rapid time of recurrence and the fact that the quality of life of the animal was affected (was not eating properly, was very lethargic and long term management with nonsteroidal anti inflammatory medication was not effective), the patient, under general anesthesia with 0.2 mg/kg medetomidine and 20 mg/kg ketamine, was euthanized using intracardiac administration of pentobarbital 1 mg/kg. Once lack of corneal reflex was confirmed, pithing was performed. Following euthanasia, the body was submitted to the Pathology Department at the University of Agricultural Sciences and Veterinary Medicine in Cluj-Napoca, Romania, for further investigation.\u003c/p\u003e\u003cp\u003eThe lizard was submitted for necropsy due to a progressively enlarging ocular mass. A well-demarcated, irregular, multilobulated mass measuring up to 2.5 cm in diameter was identified at the medial canthus of the left eye. The mass was firm yet slightly compressible, with a predominantly white to pale pink coloration. Its surface was irregular and finely granular in appearance. The mass exerted pressure on the ocular globe, causing visible indentation and mild displacement of the eye within the orbit.\u003c/p\u003e\u003cp\u003eThe surrounding eyelid was thickened and distorted, exhibiting an irregular contour due to the mass effect. Additionally, mild conjunctival hyperemia and a serous to mucoid ocular discharge were noted, likely secondary to chronic irritation and impaired tear drainage. No evidence of metastasis or other significant pathological findings was observed in the remaining organs during necropsy.\u003c/p\u003e\u003cp\u003eFor cytology, several imprint smears were prepared and routinely stained using a Diff-Quik staining kit. The prepared slides were then analyzed using an Olympus BX51 microscope, and bright-field images were captured with an Olympus SP350 digital camera. Image processing was performed using the Olympus cellSens software. The slides were well-cellularized, with a well-preserved cellular population. The cells were round to oval in shape, with indistinct borders and abundant, finely granular cytoplasm. The neoplastic cells exhibited a single large nucleus with 1–2 prominent nucleoli (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea, b). The background was moderately proteinaceous. Anisocytosis and anisokaryosis were moderate. Polarized light was used to enhance the visualization of cytoplasmic granules (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec).\u003c/p\u003e\u003cp\u003eFor histological examination, the ocular mass was preserved in 10% neutral buffered formalin (NBF) and subsequently embedded in paraffin, following a standard tissue processing protocol. Thin sections, measuring 2 micrometers, were stained with hematoxylin and eosin (H\u0026amp;E). The histopathological exam showed a well-demarcated mass composed of a dense proliferation of pigmented cells arranged in sheets and nests within a well-vascularized stroma. The neoplastic cells exhibit abundant cytoplasm containing iridescent, reflective pigment granules, characteristic of iridophores. The nuclei are round to oval with finely dispersed chromatin and occasional prominent nucleoli. Mild to moderate anisocytosis and anisokaryosis may be observed, with rare mitotic figures (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ed, e). The tumoral mass focally infiltrates the adjiacent tissue. Under polarized light, the neoplastic iridophores display bright, refractile cytoplasmic granules with a metallic or crystalline appearance, enhancing their identification within the tumor mass (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ef).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eColor changes in reptiles result from the response of dermal chromatophores to nervous and/or endocrine stimulation [7]. The integrated nature of responses of xanthophores, iridophores, and melanophores, which together constitute the dermal chromatophore unit, provides the means for the rapid color change of amphibians in response to hormonal stimulation [8].\u003c/p\u003e\u003cp\u003eAn understanding of the fundamental morphological characteristics of reptilian skin is essential for recognizing and interpreting pathological changes. The integument of reptiles is composed of the epidermis and the dermis. The epidermis consists of three layers. The inner layer is called the stratum germination, which contains cuboidal cells that produce keratin in two forms: alpha-keratin, which is flexible and located between the scales, and beta-keratin, which provides strength and hardness. In addition, it has an intermediate layer with a water-proving barrier, containing a membrane rich in lipids, and the outermost layer, the stratum corneum, is highly keratinized, where scales are formed [2, 9]. The dermis contains a conjunctival portion that comes from the underlying mesoderm, rich in collagen, blood vessels, sensory receptors, nerves, fibroblasts, histiocytes, plasma cells, reticulocytes, and chromatophores, obtaining a primary function of nourishing the epidermis and adhering to the skin. musculature through connective tissue.\u003c/p\u003e\u003cp\u003eMost reports of skin tumors in reptiles are based on individual case studies and primarily include squamous cell carcinomas (SCCs), papillomas, and chromatophoromas. [8].\u003c/p\u003e\u003cp\u003eThe diagnosis of neoplasms in reptiles can often be difficult to establish during the initial evaluation due to the nonspecific nature of the associated clinical signs [10].\u003c/p\u003e\u003cp\u003eReports of skin tumors in reptiles are largely derived from single cases and mainly comprise squamous cell carcinomas (SCCs), papillomas, and chromatophoromas [6]. The main differential diagnoses include squamous cell carcinoma, papiloma, and melanophoroma. Cutaneous neoplasms in reptiles are commonly reported as isolated cases; among current reports, squamous cell carcinoma stands out as the most common, followed by papilloma and chromatophoromas [11].\u003c/p\u003e\u003cp\u003eHistopathology and cytology are essential for differentiating between iridophoromas, melanophoromas, squamous cell carcinomas (SCCs), and papillomas in reptiles. Iridophoromas contain guanine platelets arranged in reflective stacks, exhibit birefringence under polarized light, and lack melanin pigmentation. In contrast, melanophoromas are heavily pigmented due to melanosomes, which stain positively with Fontana-Masson and display cellular pleomorphism, anisocytosis, and anisokaryosis [3,5,12]. SCCs, among the most frequently diagnosed neoplasms in reptiles, exhibit epidermal hyperplasia, keratinocyte dysplasia, karyomegaly, nuclear hyperchromatism, and mitotic figures in basal and suprabasal keratinocytes, with a loss of polarity in affected cells [13,14]. Papillomas, in contrast, are benign epithelial tumors associated with papillomavirus infections, characterized by basal cell hyperplasia, acanthosis, hyperkeratosis, and intranuclear inclusion bodies. Unlike papillomas, iridophoromas lack papillary architecture and keratinization, remaining confined to the dermis [15]. These histopathological differences are crucial for accurate diagnosis and appropriate treatment selection.\u003c/p\u003e\u003cp\u003eWhile chromatophoromas typically originate in the skin of the head and body [3,4], they have also been reported in other anatomical locations, indicating a wider potential for distribution (Table\u0026nbsp;1.).\u003c/p\u003e\u003cp\u003eTable\u0026nbsp;1. Documented Cases of Chromatophoromas in reptiles and fish: Breed, Age, Tumour type and Localisation\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"No\" id=\"Taba\" border=\"1\"\u003e\u003ccolgroup cols=\"6\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eN\u003c/p\u003e\u003cp\u003eo\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eBreed\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eAge\u003c/p\u003e\u003cp\u003e(years)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eTumour Type\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eLocalization\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eReferences\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1.\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eGreen iguana (\u003cem\u003eIguana iguana\u003c/em\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eIridophoroma\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003ePeriocular mass\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e[16]\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e2.\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSavannah monitor\u003c/p\u003e\u003cp\u003e(\u003cem\u003eVaranus exanthematicus\u003c/em\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e13\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMalignant Non-Pigmented Chromatophoroma\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eOral\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e[17]\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e3.\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eVeiled chameleon (\u003cem\u003eChamaeleo calyptratus\u003c/em\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMixed Chromatophoroma with Cutaneous, Pulmonary, and Testicular Metastases\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eRight mandible\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e[18]\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e4.\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eBearded dragon (\u003cem\u003ePogona vitticeps\u003c/em\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eAdult\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMalignant chromatophoroma\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eLeft caudal aspect of the cranium\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e[4]\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e5.\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDay Gecko (\u003cem\u003ePhelsuma madagarescencis grandis\u003c/em\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMalignant chromatophoroma\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eOuter distal portion of the right thigh\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e[19]\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e6.\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSiamese fighting fish (\u003cem\u003eBetta splendens)\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMixed chromatophoroma (benign irido-melanocytoma)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eBase of the caudal peduncle\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e[20]\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e7.\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSiamese fighting fish (\u003cem\u003eBetta splendens\u003c/em\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eChromatophoroma\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eRight eye\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e[21]\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e8.\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCrevice kelpfish (\u003cem\u003eGibbonsia montereyensis)\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eChromatophoroma\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eRight side of the head\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e[9]\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e9.\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eLargemouth bass (\u003cem\u003eMicropterus salmoides\u003c/em\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eChromatophoroma\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eVentrocaudal to the right eye\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e[22]\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e10.\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eBetta fish (\u003cem\u003eBetta splendens\u003c/em\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eUveal iridophoroma\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eIntraocular\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e[23]\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e11.\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eShubunkin goldfish\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eNS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eCornea\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e[24]\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e12.\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eEastern yellowbelly racer (Columber constrictor flaviventris)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eSubadult\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMultiple Chromatophoromas\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eThe dorsal and right epaxial musculature\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e[25]\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"6\"\u003eNS, not specified.\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis is the first documented case of iridophoroma in a tegu (\u003cem\u003eSalvator merianae\u003c/em\u003e), emphasizing the need for greater awareness and precision in reptile tumor diagnosis. Early surgical intervention with wide margins is recommended to prevent recurrence. The findings highlight the importance of paraclinical investigations in confirming rare conditions and distinguishing iridophoromas from squamous cell carcinoma, papilloma, or melanophoroma. Accurate diagnosis is essential for guiding treatment and improving outcomes in reptile medicine\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eNS, not specified. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eSCC, squamous cell carcinoma.\u003c/p\u003e\n\u003cp\u003eNBF, neutral buffered formalin.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eAcknowledgements\u003c/p\u003e\n\u003cp\u003eNot applicable\u003cbr\u003e\u0026nbsp;Author contributions\u003cbr\u003e\u0026nbsp;SC: Conceptualization, Data curation, Writing \u0026ndash; original draft. RP: Writing \u0026ndash; review \u0026amp; editing. L-VB: Writing \u0026ndash; review \u0026amp; editing. IM: review \u0026amp; editing. A-FT: Investigation, Writing \u0026ndash; review \u0026amp; editing.\u003c/p\u003e\n\u003cp\u003eFunding\u003c/p\u003e\n\u003cp\u003eThe author(s) declare that financial support was received for the research, authorship, and/or publication of this article. The University of Agriculture Science and Veterinary Medicine Cluj-Napoca, Romania.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;Data availability\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;The original contributions presented in the study are included in the article/supplementary material; further inquiries can be directed to the corresponding author.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;Ethics approval and consent to participate\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;The animal studies were approved by the University Ethics Committee and the Bioethics Subcommittee for Experiments on Animals, Plants, or Human Subjects. University of Agriculture Science and Veterinary Medicine Cluj-Napoca, Romania. The studies were conducted by the local legislation and institutional requirements. Written informed consent was obtained from the owners for the participation of their animals in this study.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;Consent for publication\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;Written informed consent was obtained from the owner of the tegu for the publication of the case report.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;Competing interests\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;The authors declare no competing interests.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eDiniz SLP, Oliveira Filho HS, Santos KM, Duarte JLC, Oliveira RL, Pierezan F, et al. Gross, histologic, and ultrastructural features of iridophoromas in Siamese fighting fish (Betta splendens). Vet Pathol. 2024. https://doi.org/10.1177/03009858241281887\u003c/li\u003e\n\u003cli\u003eGuo L, Bloom J, Sykes S, Huang E, Kashif Z, Pham E, et al. Genetics of white color and iridophoroma in \u0026ldquo;Lemon Frost\u0026rdquo; leopard geckos. PLoS Genet. 2021;17(6). https://doi.org/10.1371/journal.pgen.1009580\u003c/li\u003e\n\u003cli\u003eSilva S, de Freitas LR, Pereira LP, da Silva MEM, Chinen KH, Bandarra MB. First report of melanophoroma in Salvator merianae. Braz J Vet Pathol. 2024;17(2):104\u0026ndash;7.\u003c/li\u003e\n\u003cli\u003eStrunk A, Haney S, Reavill D. Malignant chromatophoroma in a bearded dragon (Pogona vitticeps). In: Proc Assoc Rept Amphib Vet. 2009;73\u0026ndash;6.\u003c/li\u003e\n\u003cli\u003eHeckers KO, Aupperle H, Schmidt V, Pees M. Melanophoromas and iridophoromas in reptiles. J Comp Pathol. 2012;146(2\u0026ndash;3):258\u0026ndash;68. https://doi.org/10.1016/j.jcpa.2011.07.003\u003c/li\u003e\n\u003cli\u003eGarner MM, Hernandez-Divers SM, Raymond JT. Reptile neoplasia: a retrospective study of case submissions to a specialty diagnostic service. Vet Clin North Am Exot Anim Pract. 2004;7(3):653\u0026ndash;71. https://doi.org/10.1016/j.cvex.2004.04.002\u003c/li\u003e\n\u003cli\u003eParker GH. Animal colour changes and their neurohumours: a survey of investigations 1910\u0026ndash;1943. Cambridge: Cambridge University Press; 2012. https://books.google.com/books?id=8OKAEmARDIoC\u003c/li\u003e\n\u003cli\u003eSykes JM IV, Trupkiewicz JG. Reptile neoplasia at the Philadelphia Zoological Garden, 1901\u0026ndash;2002. J Zoo Wildl Med. 2006;37(1):11\u0026ndash;9. https://doi.org/10.1638/04-112.1\u003c/li\u003e\n\u003cli\u003eCamus MS, Hyatt MW, Clauss TM, Berliner AL, Camus AC. Chromatophoroma in a crevice kelpfish (Gibbonsia montereyensis). Vet Clin Pathol. 2011;40(4):549\u0026ndash;52. https://doi.org/10.1111/j.1939-165X.2011.00365.x\u003c/li\u003e\n\u003cli\u003eTaylor JD, Hadley ME. Chromatophores and color change in the lizard, Anolis carolinensis. Z Zellforsch. 1970;104.\u003c/li\u003e\n\u003cli\u003eKubiak M, Denk D, Stidworthy MF. Retrospective review of neoplasms of captive lizards in the United Kingdom. Vet Rec. 2020;186(1):28. https://doi.org/10.1136/vr.105308\u003c/li\u003e\n\u003cli\u003ede Freitas SSLR, de Paula Pereira L, da Silva MEM, Chinen KH, Bandarra MB. First report of melanophoroma in Salvator merianae. Braz J Vet Pathol. 2024;17(2):104\u0026ndash;7. https://doi.org/10.24070/bjvp.1983-0246.v17i2p104-107\u003c/li\u003e\n\u003cli\u003eSolanes Vilanova F, Hellebuyck T, Chiers K. Histological variants of squamous and basal cell carcinoma in squamates and chelonians: a comprehensive classification. Animals (Basel). 2023;13(8). https://doi.org/10.3390/ani13081327\u003c/li\u003e\n\u003cli\u003eSolanes-Vilanova F, Chiers K, Gil-Lianes J, Hellebuyck T. Clinical features, surgical management and outcome of squamous and basal cell carcinoma in squamates and chelonians. Vet Dermatol. 2024;35(6):626\u0026ndash;40. https://doi.org/10.1111/vde.13282\u003c/li\u003e\n\u003cli\u003eMeuten DJ. Tumors in domestic animals. 5th ed. Ames: Wiley-Blackwell; 2017.\u003c/li\u003e\n\u003cli\u003eRousselet E, de Mello Souza CH, Wellehan JFX, Epperson ED, Dark MJ, Wamsley HL. Cutaneous iridophoroma in a green iguana (Iguana iguana). Vet Clin Pathol. 2017;46(4):625\u0026ndash;8. https://doi.org/10.1111/vcp.12536\u003c/li\u003e\n\u003cli\u003eDurska M, Mikiewicz M, Paździor-Czapula K, Gesek M, Otrocka-Domagała I. Histopathological and immunohistochemical evaluation of malignant non-pigmented chromatophoroma in a savannah monitor (Varanus exanthematicus) \u0026ndash; a case study. 2024. https://doi.org/10.2139/ssrn.4885623\u003c/li\u003e\n\u003cli\u003eLewis N, Martinson S, Wadowska D, Desmarchelier M. Malignant mixed chromatophoroma with cutaneous, pulmonary, and testicular metastases in a veiled chameleon (Chamaeleo calyptratus). J Herpetol Med Surg. 2015;25(1\u0026ndash;2):16. https://doi.org/10.5818/1529-9651-25.1.16\u003c/li\u003e\n\u003cli\u003eMikaelian I, Lynch S, Harshbarger JC, Reavill DR. Malignant chromatophoroma in a day gecko (Phelsuma madagascariensis grandis). 2007.\u003c/li\u003e\n\u003cli\u003eShivley JM, Brookshire WC, Baumgartner WA. Mixed chromatophoroma (benign irido-melanocytoma) in a male Siamese fighting fish, Betta splendens, Regan. J Fish Dis. 2021;44(3):351\u0026ndash;4. https://doi.org/10.1111/jfd.13303\u003c/li\u003e\n\u003cli\u003eCiambrone C, Chen LR, Tokarz DA, Lewbart GA. Chromatophoroma in a Siamese fighting fish (Betta splendens). Vet Rec Case Rep. 2019;7(2):e000840. https://doi.org/10.1136/vetreccr-2019-000840\u003c/li\u003e\n\u003cli\u003eYaw TJ, Michaels B, Reavill D, Zaffarano BA. Liquid nitrogen cryosurgery for a chromatophoroma in a captive largemouth bass (Micropterus salmoides). J Exotic Pet Med. 2016;25(4):305\u0026ndash;10. https://doi.org/10.1053/j.jepm.2016.07.001\u003c/li\u003e\n\u003cli\u003eCrevoiserat L, Katzenstein N, LaDouceur EEB. Uveal iridophoroma in a betta fish (Betta splendens). J Comp Pathol. 2024;215:71\u0026ndash;5. https://doi.org/10.1016/j.jcpa.2024.09.006\u003c/li\u003e\n\u003cli\u003eKim S, Moore BA, Parker C, Siniard WC, Ang J, Teixeira LBC, et al. Clinical and histopathological features of proliferative corneal lesions in Cyprininae fishes: implications for treatment and insights into corneal tumors. Vet Ophthalmol. 2024;27(3):200\u0026ndash;13. https://doi.org/10.1111/vop.13133\u003c/li\u003e\n\u003cli\u003eSuedmeyer WK, Garner JNB, Franklin AF. Diagnosis and clinical management of multiple chromatophoromas in an eastern yellowbelly racer (Coluber constrictor flaviventris). J Zoo Wildl Med. n.d.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-veterinary-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [BMC Veterinary Research](http://bmcvetres.biomedcentral.com/)","snPcode":"12917","submissionUrl":"https://submission.nature.com/new-submission/12917/3?","title":"BMC Veterinary Research","twitterHandle":"@BMC_series","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Iridophoroma, Tegu (Salvator merianae), Reptile tumor, Ocular neoplasia","lastPublishedDoi":"10.21203/rs.3.rs-7029183/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7029183/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground:\u003c/strong\u003e\u003cbr\u003e\nThis case report describes the clinical and histological findings of a rare ocular iridophoroma in a tegu.\u003cbr\u003e\n\u003cstrong\u003eCase presentation:\u003c/strong\u003e Iridophoroma is a rare type of chromatophoroma, a tumor that arises from iridophores, specialized pigment cells responsible for reflecting light. This case report describes a 6-year-old male Argentine black and white tegu (\u003cem\u003eSalvator merianae\u003c/em\u003e) presented with a large, irregular, proliferative mass in the periocular region. The mass originated from the upper left eyelid, partially obstructing the ocular surface, and measured 2.5 cm in diameter. The patient was referred to the department of Surgery and Intensive care for mass removal and underwent two separate surgical resections. Fine needle aspiration from the structure revealed the diagnosis of iridophoroma, which was later confirmed through histology. This case aims to broaden current knowledge in reptile medicine by presenting an iridophoroma in \u003cem\u003eSalvator merianae\u003c/em\u003e, highlighting its clinical presentation, cytological features, and histopathological aspects.\u003cbr\u003e\n\u003cstrong\u003eConclusions:\u003c/strong\u003e\u003cbr\u003e\nThis case represents the first documented occurrence of an iridophoroma in a tegu, highlighting the need for increased awareness and precision in diagnosing tumors in reptiles. The findings demonsrate the importance of paraclinical investigations, such as histopathology, not only in confirming rare conditions but also in differentiating iridophoromas from other potential diagnoses, such as squamous cell carcinoma, papilloma, or melanophoroma. Accurate identification is crucial for guiding appropriate treatment and improving outcomes in reptile medicine.\u003c/p\u003e","manuscriptTitle":"First Report of an Iridophoroma in a Tegu (Salvator merianae)","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-01 10:10:45","doi":"10.21203/rs.3.rs-7029183/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-11-20T17:43:19+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-09-13T17:43:58+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"180062324704494420536473643622012095656","date":"2025-08-23T16:08:08+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"56523282223609523890107747768734238990","date":"2025-08-22T21:55:59+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-08-22T14:04:31+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"131095740129201451548830830807327124666","date":"2025-08-22T03:45:45+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-08-21T15:34:50+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-07-23T13:09:52+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-07-23T06:43:53+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-07-21T11:15:39+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Veterinary Research","date":"2025-07-21T11:13:17+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-veterinary-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [BMC Veterinary Research](http://bmcvetres.biomedcentral.com/)","snPcode":"12917","submissionUrl":"https://submission.nature.com/new-submission/12917/3?","title":"BMC Veterinary Research","twitterHandle":"@BMC_series","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"42f8420e-7d8c-4f7a-a4d0-5092f0372702","owner":[],"postedDate":"September 1st, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2026-03-02T16:05:18+00:00","versionOfRecord":{"articleIdentity":"rs-7029183","link":"https://doi.org/10.1186/s12917-025-05255-0","journal":{"identity":"bmc-veterinary-research","isVorOnly":false,"title":"BMC Veterinary Research"},"publishedOn":"2026-02-26 15:58:37","publishedOnDateReadable":"February 26th, 2026"},"versionCreatedAt":"2025-09-01 10:10:45","video":"","vorDoi":"10.1186/s12917-025-05255-0","vorDoiUrl":"https://doi.org/10.1186/s12917-025-05255-0","workflowStages":[]},"version":"v1","identity":"rs-7029183","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7029183","identity":"rs-7029183","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}