Isolated hydatid cyst in the medial rectus muscle: unveiling a rare orbital occurrence

Isolated hydatid cyst in the medial rectus muscle: unveiling a rare orbital occurrence | 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 Short Report Isolated hydatid cyst in the medial rectus muscle: unveiling a rare orbital occurrence Alireza Attar, behzad Khademi, Mohammad Hassan Jalalpour This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4752323/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 12 Nov, 2024 Read the published version in Journal of Ophthalmic Inflammation and Infection → Version 1 posted 15 You are reading this latest preprint version Abstract Background Orbital hydatid disease, while rare, should be included in the differential diagnosis of unilateral proptosis, particularly in endemic areas. Accurate diagnosis and comprehensive management are essential for effective treatment and favorable long-term outcomes. Case Presentation A 12-year-old boy presented with a one-month history of diplopia and left-sided proptosis. A CT scan revealed a cystic mass within the left medial rectus muscle. Surgical intervention confirmed the presence of a hydatid cyst following cyst rupture and irrigation with hypertonic saline. The patient underwent a two-month course of albendazole therapy. Initially, the patient experienced persistent exotropia and diplopia, but at the three-year follow-up, he exhibited no diplopia or proptosis and only mild residual exotropia. Conclusion This case underscores the importance of considering orbital hydatid cysts in the differential diagnosis of unilateral proptosis in endemic regions. Heightened awareness, accurate diagnosis, and a tailored therapeutic approach, including surgical removal and antiparasitic treatment, are crucial for successful management and improved long-term outcomes. Figures Figure 1 Figure 2 Figure 3 Introduction Hydatid disease, resulting from the infestation of larvae of the tapeworm Echinococcus granulosus, exhibits varying incidence rates across different geographical regions. This disease is particularly prevalent in underdeveloped countries and areas where sheep farming is common( 1 ).Hydatidosis can affect nearly every organ or tissue in the body through portal or systemic circulation( 2 ). In humans, the liver and lungs are the most commonly affected sites, with the central nervous system involved in 2–3% of cases( 3 ). While hydatid cysts can form in any organ, orbital involvement is especially uncommon, representing less than 1% of all cases( 4 ). Despite its rarity, orbital hydatidosis is a crucial differential diagnosis for unilateral exophthalmos in patients from regions where echinococcosis is endemic( 5 ). This study highlights a rare case of a young man presenting with proptosis and diplopia persisting for one month. Diagnosis revealed an isolated hydatid cyst, initially undetected until pathological examination. This report adhered to the ethical principles outlined in the Declaration of Helsinki. Case report A 12-year-old male presented with complaints of diplopia and left-sided proptosis persisting for one month. He had no relevant medical history and no known exposure to animals such as dogs or sheep. His visual acuity was 20/20 in both eyes, with limited ocular motility in the medial direction on the left side (− 4). Hertel measurements were 15 mm on the right side and 20 mm on the left at a base of 92 mm (Fig. 1 -A). The margin of the left optic disc was blurred. The remainder of the ocular examination was normal. A CT scan revealed a cystic mass within the left medial rectus. The eyeball was non-reducible and non-pulsatile. Axial and coronal orbital CT scans showed a well-defined, medio-inferiorly localized cystic lesion measuring 2 × 2 × 2.5 cm (Fig. 2). Routine blood tests, including erythrocyte sedimentation rate, yielded normal results. Blood chemistry analysis also revealed normal findings, without evidence of hypereosinophilia. In pathology, a sample stained with Hematoxylin and Eosin (H&E) revealed an acellular laminated membrane with a germinal epithelium and daughter cysts containing protoscolices (Fig. 3 ). During the surgical procedure, a combined lateral orbitotomy with bone window and transconjunctival medial orbitotomy was performed. Dissection was conducted laterally from the optic nerve and medially from the medial rectus muscle. During the operation, a large cyst was encountered. Due to the cyst's considerable size and the risk of rupture during excision, complete removal was not feasible. To mitigate the risk of spreading the cyst contents, a controlled intentional rupture was performed at one point. This was followed by irrigation with hypertonic saline. The intentional rupture and subsequent irrigation were carried out prior to the excision of the cyst to ensure the cyst contents did not disseminate. Pathological examination confirmed the presence of a hydatid cyst. An abdominopelvic ultrasound, chest X-ray, and brain CT scan showed no additional hydatid cysts. The patient was started on albendazole (400 mg twice a day), which was administered for two months. However, after 10 months, his exotropia and diplopia persisted. He had a 30-prism diopter in primary position and limited motion in adduction of the left eye (− 2). A lateral rectus recession of 6.5 mm and medial rectus resection of 4.5 mm were performed. Three years post-surgery, the patient had no diplopia or proptosis (Hertel measurements were 15 mm on the right side and 17 mm on the left at a base of 92 mm) and no recurrence of hydatid cysts, with only a 10-prism diopter in primary position exotropia remaining and limited ocular motility (− 1) in lateral gaze (Fig. 1 -B). Discussion Orbital hydatid disease, an exceptionally rare parasitic infection, is attributed to the tapeworm Echinococcus granulosus( 6 ).Like many zoonotic diseases impacting humans, orbital hydatid disease typically arises from inadvertent ingestion of eggs expelled by definitive hosts, primarily canines( 7 ). The lungs, brain, spine, and orbit are more frequently affected in children and young adults compared to older individuals( 3 ). The orbit is a particularly rare site for hydatid disease, even in regions where the condition is common, accounting for less than 1% of all cases( 8 ). The clinical presentation of hydatid disease primarily stems from the mass effect exerted by the cyst on neighboring structures(6). This effect is particularly notable in regions with restricted space, such as the orbit( 1 ). In our case, consistent with typical presentations of hydatid disease, symptoms of an orbital hydatid cyst manifested gradually. Specifically, unilateral proptosis without associated pain was observed. Other reported symptoms in previous studies encompass unilateral proptosis with or without pain, visual impairment, periorbital pain, chemosis, and headache ( 9 ). Accurate preoperative diagnosis and detailed localization are crucial for the effective management of orbital hydatid disease. Therefore, differential diagnosis should include consideration of other cystic mass lesions such as abscesses, mucoceles, intraorbital hematomas, lacrimal tumors or cysts, and lymphangiomas( 10 ). Initially, we suspected an orbital hydatid cyst and awaited pathology confirmation. The pathology report subsequently confirmed the diagnosis of a hydatid cyst. In our case, orbital hydatid cysts manifested as unilocular hypodense cysts on CT imaging. However, it's noteworthy that atypical hyperdense hydatid cysts can mimic other soft tissue orbital tumors, as observed by Sperryn et al( 11 ). On CT, typical features of orbital hydatid cysts include a unilocular, non-enhancing homogeneous cyst with low density, akin to the visualization of the vitreous body( 12 ). If there is suspicion of a hydatid cyst, MRI is preferable for the differential diagnosis of soft tissue lesions. Orbital hydatid cysts are almost invariably situated in the superolateral and superomedial angles of the orbit, lying in or close to the muscle cone( 13 ). However, in our case, the hydatid cyst was located in the medial rectus muscle and presented with restrictive exotropia. This is the second reported case of intramuscular hydatid disease in the orbit( 2 ). Surgery is the most effective treatment for an orbital hydatid cyst. While medical therapy can be considered, it is generally less effective in intraorbital echinococcosis compared to other locations of the disease. In our case, both surgery and medical therapy were used and proved to be effective. For surgical treatment, Radical surgery of the cyst is one option. Another option involves intraoperative aspiration of the cysts, which has the advantages of aiding diagnosis, reducing the size of the cyst, and causing the inner germinative layer to collapse, allowing the outer fibrous wall to be safely tented and snipped open( 14 ).In the event of intraoperative cyst rupture, irrigation with hypertonic saline and hydrogen peroxide is recommended to neutralize daughter cysts and mitigate the risk of further dissemination( 15 ). In our case, due to the large size of the cyst, intentional rupture followed by irrigation with hypertonic saline was deemed necessary. After confirmation of the hydatid cyst, we initiated treatment with albendazole. Albendazole is potentially more suitable for treating orbital cysts, as it has a broad spectrum of antiparasitic activity( 16 ). In contrast, medical therapy with mebendazole is likely ineffective in orbital hydatid disease and has no known therapeutic effect on hydatid disease of the central nervous system. Mebendazole crosses the blood-brain barrier poorly and may also penetrate the orbital region insufficiently( 17 ). In conclusion, although orbital hydatid cysts are rare, they should be considered in differential diagnoses in endemic regions. Accurate diagnosis, combined with intraoperative cyst rupture, irrigation with hypertonic saline, and antiparasitic treatment, is essential for effective management and favorable long-term outcomes without recurrence. Declarations Ethics approval and consent to participate All procedures performed in studies involving human participants were in accordance with the ethical standards of The Human Ethics Committee of Shiraz University of Medical Sciences and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. the participant in the study were fully informed about the goals, cooperation, benefits, and potential harms of the study and completed the ethical consent forms. Consent for publication The participant in the study were fully informed about the goals, cooperation, benefits, and potential harms of the study and completed the ethical consent forms. Conflict of interest Behzad khademi, Alireza attar, and Mohammad Hassan Jalalpour declare that they have no conflict of interest. Author Contribution behzad khademi contributed to the conception, design, and supervision of the study . material preparation and data collection were done by alireza attar and Mohammad Hassan Jalalpour . the manuscript was written by behzad khademi and alireza attar . all authors read and approved the final manuscript . References Fasina O, Ogun OG (2017) Hydatid cyst of the orbit in a young Nigerian female: a case report. Ghana Med J 51:204–206 Şanl M, Sabuncuoğlu H, Keskin T (2007) Primary intraorbital hydatid cyst: an unusual location, case report and review of the literature. Min-Minimally Invasive Neurosurg 50:367–369 Malik A, Chandra R, Prasad R et al (2016) Imaging appearances of atypical hydatid cysts. Indian J Radiol Imaging 26:33–39 Turgut AT, Turgut M, Koşar U (2004) Hydatidosis of the orbit in Turkey: results from review of the literature 1963–2001. Int Ophthalmol 25:193–200 Debela AS, Abore KW, Worke AB, Wendimagegn ST (2024) Primary Intra-orbital Hydatid cyst: a case report of a rare cause of Exophthalmos. Int Med Case Rep J. :89–92 Polat P, Kantarci M, Alper F et al (2003) Hydatid disease from head to toe. Radiographics 23:475–494 Ma M-S, Su F, Hei Y et al (2021) Disseminated hydatid disease in the orbit and central nervous system. Int J Ophthalmol 14:1457 Turgut AT, Turgut M, Koşar U (2004) Hydatidosis of the orbit in Turkey: results from review of the literature 1963–2001. Int Ophthalmol 25:193–200 Gökçek C, Bayar N, Buharal Z (2001) Total removal of an unruptured orbital hydatid cyst. Can J Ophthalmology/Journal canadien d'ophtalmologie 4:218–220 Torun F, Tuna H, Bozkurt M, Deda H (2004) Orbital Hydatic Cyst: Case Report. Türk Nöroşirürji Dergisi 14:184–187 Sperryn C, Corr P (1994) CT evaluation of orbital hydatid disease: a review of 10 cases. Clin Radiol 49:703–704 Öztekin PS, Yilmaz BK, Gokharman FD, Koşar PN (2014) Primary orbital hydatid cyst: computed tomography and magnetic resonance imaging findings. Singapore Med J 55:e184 Al-Muala HD, Sami SM, Shukri MA et al (2012) Orbital hydatid cyst. Ann Maxillofac Surg 2:197–199 Motie MR, Ghaemi M, Aliakbarian M, Saremi E (2010) Study of the Radical vs. Conservative Surgical Treatment of the Hepatic Hydatid Cyst: A 10-Year Experience. Indian J Surg 72:448–452 Aloua R, Slimani F (2021) Calcified hydatid cyst of the orbit. J Pediatr Surg Case Rep 64:101708 Arif SH, Malik AA, Khaja AR et al (2011) Role of albendazole in the management of hydatid cyst liver. Saudi J Gastroenterol 17:343–347 KEYSTONE JS, MURDOCH JK (1979) Drugs five years later: Mebendazole. Ann Intern Med 91:582–586 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 12 Nov, 2024 Read the published version in Journal of Ophthalmic Inflammation and Infection → Version 1 posted Editorial decision: Revision requested 06 Aug, 2024 Reviews received at journal 02 Aug, 2024 Reviews received at journal 30 Jul, 2024 Reviews received at journal 24 Jul, 2024 Reviewers agreed at journal 24 Jul, 2024 Reviewers agreed at journal 24 Jul, 2024 Reviewers agreed at journal 23 Jul, 2024 Reviewers agreed at journal 22 Jul, 2024 Reviewers agreed at journal 22 Jul, 2024 Reviewers agreed at journal 22 Jul, 2024 Reviewers agreed at journal 22 Jul, 2024 Reviewers invited by journal 22 Jul, 2024 Editor assigned by journal 17 Jul, 2024 Submission checks completed at journal 17 Jul, 2024 First submitted to journal 16 Jul, 2024 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. 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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-4752323","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Short Report","associatedPublications":[],"authors":[{"id":336742261,"identity":"42734aa3-92bf-414f-a731-297bba0cedad","order_by":0,"name":"Alireza Attar","email":"","orcid":"","institution":"Shiraz University of Medical Sciences","correspondingAuthor":false,"prefix":"","firstName":"Alireza","middleName":"","lastName":"Attar","suffix":""},{"id":336742262,"identity":"c90f12dc-625a-4ee4-899d-8b27e9a4f7e4","order_by":1,"name":"behzad Khademi","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABAElEQVRIiWNgGAWjYBACCQkgBiEDBh4gl80GSDA2HiBFSxpISwMxWhhgWg6DRfFqkZzd/PDGxxwLBnP23sMffpSdt1vbfhhoS41NNC4t0jLHjC1nbpNgsOw5l2DYc+528rYziUAtx9JyG3BokZNIMJPmBWoxuJFjkMDbdjvZ7ABQC2PDYTxa0r9J/wVpuf/G4ODftnPJZucf4tciLZFjJs0ItoXHsJm37YCd2Q0CtkjOyCm27N0mwWPZk2PMLHMuOcHsBtCWBDx+kbiRvvHGz211cubsZ4w/vimzszc7n/7wwYcaG5xaYIAHxkgEq0wgoBwF2JOieBSMglEwCkYGAAAtImBAjVn8wgAAAABJRU5ErkJggg==","orcid":"","institution":"Shiraz University of Medical Sciences","correspondingAuthor":true,"prefix":"","firstName":"behzad","middleName":"","lastName":"Khademi","suffix":""},{"id":336742263,"identity":"85e5eb2d-992a-4d2e-b18b-e8bc925bd16a","order_by":2,"name":"Mohammad Hassan Jalalpour","email":"","orcid":"","institution":"Shiraz University of Medical Sciences","correspondingAuthor":false,"prefix":"","firstName":"Mohammad","middleName":"Hassan","lastName":"Jalalpour","suffix":""}],"badges":[],"createdAt":"2024-07-16 20:56:56","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4752323/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4752323/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s12348-024-00436-8","type":"published","date":"2024-11-12T15:57:06+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":62730092,"identity":"30444f58-3d98-4d79-a4d7-9d6c6be594a0","added_by":"auto","created_at":"2024-08-18 23:11:47","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":120249,"visible":true,"origin":"","legend":"\u003cp\u003eFace photo A. Before Operation proptosis in the left eye, B.\u003c/p\u003e","description":"","filename":"figure11.png","url":"https://assets-eu.researchsquare.com/files/rs-4752323/v1/28669dd83d7636d802170043.png"},{"id":62730091,"identity":"22963567-85af-4d49-910e-68f56be8949a","added_by":"auto","created_at":"2024-08-18 23:11:47","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":99195,"visible":true,"origin":"","legend":"\u003cp\u003ein the CT scans, axial (A) and coronal (B) orbital CT images revealed a well-defined cystic lesion measuring 2 × 2 × 2.5 cm, localized inferomedially and obscured medial rectus muscle.\u003c/p\u003e","description":"","filename":"figure2.png","url":"https://assets-eu.researchsquare.com/files/rs-4752323/v1/57282eb25b7844667e87a305.png"},{"id":62730090,"identity":"450422b1-dc0c-4258-a006-290d01f596d6","added_by":"auto","created_at":"2024-08-18 23:11:47","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":66471,"visible":true,"origin":"","legend":"\u003cp\u003eHematoxylin and Eosin (H\u0026amp;E) staining; an acellular laminated membrane with germinal epithelium and daughter cysts containing protoscolices.\u003c/p\u003e","description":"","filename":"figure3.png","url":"https://assets-eu.researchsquare.com/files/rs-4752323/v1/110450a544e7d55a9ab72800.png"},{"id":69274933,"identity":"0878605b-ad27-4135-b851-68287fe016f1","added_by":"auto","created_at":"2024-11-18 16:39:40","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":516786,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4752323/v1/d3b9badf-94ea-4d77-96e4-5c88a45e306c.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Isolated hydatid cyst in the medial rectus muscle: unveiling a rare orbital occurrence","fulltext":[{"header":"Introduction","content":"\u003cp\u003eHydatid disease, resulting from the infestation of larvae of the tapeworm Echinococcus granulosus, exhibits varying incidence rates across different geographical regions. This disease is particularly prevalent in underdeveloped countries and areas where sheep farming is common(\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e).Hydatidosis can affect nearly every organ or tissue in the body through portal or systemic circulation(\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). In humans, the liver and lungs are the most commonly affected sites, with the central nervous system involved in 2\u0026ndash;3% of cases(\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e). While hydatid cysts can form in any organ, orbital involvement is especially uncommon, representing less than 1% of all cases(\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e). Despite its rarity, orbital hydatidosis is a crucial differential diagnosis for unilateral exophthalmos in patients from regions where echinococcosis is endemic(\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e). This study highlights a rare case of a young man presenting with proptosis and diplopia persisting for one month. Diagnosis revealed an isolated hydatid cyst, initially undetected until pathological examination.\u003c/p\u003e \u003cp\u003eThis report adhered to the ethical principles outlined in the Declaration of Helsinki.\u003c/p\u003e"},{"header":"Case report","content":"\u003cp\u003eA 12-year-old male presented with complaints of diplopia and left-sided proptosis persisting for one month. He had no relevant medical history and no known exposure to animals such as dogs or sheep. His visual acuity was 20/20 in both eyes, with limited ocular motility in the medial direction on the left side (\u0026minus;\u0026thinsp;4). Hertel measurements were 15 mm on the right side and 20 mm on the left at a base of 92 mm (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e-A). The margin of the left optic disc was blurred. The remainder of the ocular examination was normal.\u003c/p\u003e \u003cp\u003eA CT scan revealed a cystic mass within the left medial rectus. The eyeball was non-reducible and non-pulsatile. Axial and coronal orbital CT scans showed a well-defined, medio-inferiorly localized cystic lesion measuring 2 \u0026times; 2 \u0026times; 2.5 cm (Fig.\u0026nbsp;2). Routine blood tests, including erythrocyte sedimentation rate, yielded normal results. Blood chemistry analysis also revealed normal findings, without evidence of hypereosinophilia. In pathology, a sample stained with Hematoxylin and Eosin (H\u0026amp;E) revealed an acellular laminated membrane with a germinal epithelium and daughter cysts containing protoscolices (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eDuring the surgical procedure, a combined lateral orbitotomy with bone window and transconjunctival medial orbitotomy was performed. Dissection was conducted laterally from the optic nerve and medially from the medial rectus muscle. During the operation, a large cyst was encountered. Due to the cyst's considerable size and the risk of rupture during excision, complete removal was not feasible. To mitigate the risk of spreading the cyst contents, a controlled intentional rupture was performed at one point. This was followed by irrigation with hypertonic saline. The intentional rupture and subsequent irrigation were carried out prior to the excision of the cyst to ensure the cyst contents did not disseminate. Pathological examination confirmed the presence of a hydatid cyst. An abdominopelvic ultrasound, chest X-ray, and brain CT scan showed no additional hydatid cysts. The patient was started on albendazole (400 mg twice a day), which was administered for two months. However, after 10 months, his exotropia and diplopia persisted. He had a 30-prism diopter in primary position and limited motion in adduction of the left eye (\u0026minus;\u0026thinsp;2). A lateral rectus recession of 6.5 mm and medial rectus resection of 4.5 mm were performed.\u003c/p\u003e \u003cp\u003eThree years post-surgery, the patient had no diplopia or proptosis (Hertel measurements were 15 mm on the right side and 17 mm on the left at a base of 92 mm) and no recurrence of hydatid cysts, with only a 10-prism diopter in primary position exotropia remaining and limited ocular motility (\u0026minus;\u0026thinsp;1) in lateral gaze (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e-B).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eOrbital hydatid disease, an exceptionally rare parasitic infection, is attributed to the tapeworm Echinococcus granulosus(\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e).Like many zoonotic diseases impacting humans, orbital hydatid disease typically arises from inadvertent ingestion of eggs expelled by definitive hosts, primarily canines(\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e). The lungs, brain, spine, and orbit are more frequently affected in children and young adults compared to older individuals(\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e). The orbit is a particularly rare site for hydatid disease, even in regions where the condition is common, accounting for less than 1% of all cases(\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e). The clinical presentation of hydatid disease primarily stems from the mass effect exerted by the cyst on neighboring structures(6). This effect is particularly notable in regions with restricted space, such as the orbit(\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e). In our case, consistent with typical presentations of hydatid disease, symptoms of an orbital hydatid cyst manifested gradually. Specifically, unilateral proptosis without associated pain was observed. Other reported symptoms in previous studies encompass unilateral proptosis with or without pain, visual impairment, periorbital pain, chemosis, and headache (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e). Accurate preoperative diagnosis and detailed localization are crucial for the effective management of orbital hydatid disease. Therefore, differential diagnosis should include consideration of other cystic mass lesions such as abscesses, mucoceles, intraorbital hematomas, lacrimal tumors or cysts, and lymphangiomas(\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e). Initially, we suspected an orbital hydatid cyst and awaited pathology confirmation. The pathology report subsequently confirmed the diagnosis of a hydatid cyst. In our case, orbital hydatid cysts manifested as unilocular hypodense cysts on CT imaging. However, it's noteworthy that atypical hyperdense hydatid cysts can mimic other soft tissue orbital tumors, as observed by Sperryn et al(\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e). On CT, typical features of orbital hydatid cysts include a unilocular, non-enhancing homogeneous cyst with low density, akin to the visualization of the vitreous body(\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e). If there is suspicion of a hydatid cyst, MRI is preferable for the differential diagnosis of soft tissue lesions. Orbital hydatid cysts are almost invariably situated in the superolateral and superomedial angles of the orbit, lying in or close to the muscle cone(\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e). However, in our case, the hydatid cyst was located in the medial rectus muscle and presented with restrictive exotropia. This is the second reported case of intramuscular hydatid disease in the orbit(\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). Surgery is the most effective treatment for an orbital hydatid cyst. While medical therapy can be considered, it is generally less effective in intraorbital echinococcosis compared to other locations of the disease. In our case, both surgery and medical therapy were used and proved to be effective.\u003c/p\u003e \u003cp\u003eFor surgical treatment, Radical surgery of the cyst is one option. Another option involves intraoperative aspiration of the cysts, which has the advantages of aiding diagnosis, reducing the size of the cyst, and causing the inner germinative layer to collapse, allowing the outer fibrous wall to be safely tented and snipped open(\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e).In the event of intraoperative cyst rupture, irrigation with hypertonic saline and hydrogen peroxide is recommended to neutralize daughter cysts and mitigate the risk of further dissemination(\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e). In our case, due to the large size of the cyst, intentional rupture followed by irrigation with hypertonic saline was deemed necessary.\u003c/p\u003e \u003cp\u003eAfter confirmation of the hydatid cyst, we initiated treatment with albendazole. Albendazole is potentially more suitable for treating orbital cysts, as it has a broad spectrum of antiparasitic activity(\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e). In contrast, medical therapy with mebendazole is likely ineffective in orbital hydatid disease and has no known therapeutic effect on hydatid disease of the central nervous system. Mebendazole crosses the blood-brain barrier poorly and may also penetrate the orbital region insufficiently(\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn conclusion, although orbital hydatid cysts are rare, they should be considered in differential diagnoses in endemic regions. Accurate diagnosis, combined with intraoperative cyst rupture, irrigation with hypertonic saline, and antiparasitic treatment, is essential for effective management and favorable long-term outcomes without recurrence.\u003c/p\u003e "},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eEthics approval and consent to participate\u003c/h2\u003e \u003cp\u003eAll procedures performed in studies involving human participants were in accordance with the ethical standards of The Human Ethics Committee of Shiraz University of Medical Sciences and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. the participant in the study were fully informed about the goals, cooperation, benefits, and potential harms of the study and completed the ethical consent forms.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eConsent for publication\u003c/strong\u003e \u003cp\u003eThe participant in the study were fully informed about the goals, cooperation, benefits, and potential harms of the study and completed the ethical consent forms.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eConflict of interest\u003c/strong\u003e \u003cp\u003eBehzad khademi, Alireza attar, and Mohammad Hassan Jalalpour declare that they have no conflict of interest.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003ebehzad khademi contributed to the conception, design, and supervision of the study . material preparation and data collection were done by alireza attar and Mohammad Hassan Jalalpour . the manuscript was written by behzad khademi and alireza attar . all authors read and approved the final manuscript .\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eFasina O, Ogun OG (2017) Hydatid cyst of the orbit in a young Nigerian female: a case report. Ghana Med J 51:204\u0026ndash;206\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eŞanl M, Sabuncuoğlu H, Keskin T (2007) Primary intraorbital hydatid cyst: an unusual location, case report and review of the literature. Min-Minimally Invasive Neurosurg 50:367\u0026ndash;369\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMalik A, Chandra R, Prasad R et al (2016) Imaging appearances of atypical hydatid cysts. Indian J Radiol Imaging 26:33\u0026ndash;39\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTurgut AT, Turgut M, Koşar U (2004) Hydatidosis of the orbit in Turkey: results from review of the literature 1963\u0026ndash;2001. Int Ophthalmol 25:193\u0026ndash;200\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDebela AS, Abore KW, Worke AB, Wendimagegn ST (2024) Primary Intra-orbital Hydatid cyst: a case report of a rare cause of Exophthalmos. Int Med Case Rep J. :89\u0026ndash;92\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePolat P, Kantarci M, Alper F et al (2003) Hydatid disease from head to toe. Radiographics 23:475\u0026ndash;494\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMa M-S, Su F, Hei Y et al (2021) Disseminated hydatid disease in the orbit and central nervous system. Int J Ophthalmol 14:1457\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTurgut AT, Turgut M, Koşar U (2004) Hydatidosis of the orbit in Turkey: results from review of the literature 1963\u0026ndash;2001. Int Ophthalmol 25:193\u0026ndash;200\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eG\u0026ouml;k\u0026ccedil;ek C, Bayar N, Buharal Z (2001) Total removal of an unruptured orbital hydatid cyst. Can J Ophthalmology/Journal canadien d'ophtalmologie 4:218\u0026ndash;220\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTorun F, Tuna H, Bozkurt M, Deda H (2004) Orbital Hydatic Cyst: Case Report. T\u0026uuml;rk N\u0026ouml;roşir\u0026uuml;rji Dergisi 14:184\u0026ndash;187\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSperryn C, Corr P (1994) CT evaluation of orbital hydatid disease: a review of 10 cases. Clin Radiol 49:703\u0026ndash;704\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003e\u0026Ouml;ztekin PS, Yilmaz BK, Gokharman FD, Koşar PN (2014) Primary orbital hydatid cyst: computed tomography and magnetic resonance imaging findings. Singapore Med J 55:e184\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAl-Muala HD, Sami SM, Shukri MA et al (2012) Orbital hydatid cyst. Ann Maxillofac Surg 2:197\u0026ndash;199\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMotie MR, Ghaemi M, Aliakbarian M, Saremi E (2010) Study of the Radical vs. Conservative Surgical Treatment of the Hepatic Hydatid Cyst: A 10-Year Experience. Indian J Surg 72:448\u0026ndash;452\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAloua R, Slimani F (2021) Calcified hydatid cyst of the orbit. J Pediatr Surg Case Rep 64:101708\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eArif SH, Malik AA, Khaja AR et al (2011) Role of albendazole in the management of hydatid cyst liver. Saudi J Gastroenterol 17:343\u0026ndash;347\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKEYSTONE JS, MURDOCH JK (1979) Drugs five years later: Mebendazole. Ann Intern Med 91:582\u0026ndash;586\u003c/span\u003e\u003c/li\u003e \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":"journal-of-ophthalmic-inflammation-and-infection","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"joii","sideBox":"Learn more about [Journal of Ophthalmic Inflammation and Infection](http://joii-journal.springeropen.com)","snPcode":"12348","submissionUrl":"https://submission.nature.com/new-submission/12348/3","title":"Journal of Ophthalmic Inflammation and Infection","twitterHandle":"@SpringerOpen","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-4752323/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4752323/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eBackground\u003c/p\u003e\n\u003cp\u003eOrbital hydatid disease, while rare, should be included in the differential diagnosis of unilateral proptosis, particularly in endemic areas. Accurate diagnosis and comprehensive management are essential for effective treatment and favorable long-term outcomes.\u003c/p\u003e\n\u003cp\u003eCase Presentation\u003c/p\u003e\n\u003cp\u003eA 12-year-old boy presented with a one-month history of diplopia and left-sided proptosis. A CT scan revealed a cystic mass within the left medial rectus muscle. Surgical intervention confirmed the presence of a hydatid cyst following cyst rupture and irrigation with hypertonic saline. The patient underwent a two-month course of albendazole therapy. Initially, the patient experienced persistent exotropia and diplopia, but at the three-year follow-up, he exhibited no diplopia or proptosis and only mild residual exotropia.\u003c/p\u003e\n\u003cp\u003eConclusion\u003c/p\u003e\n\u003cp\u003eThis case underscores the importance of considering orbital hydatid cysts in the differential diagnosis of unilateral proptosis in endemic regions. Heightened awareness, accurate diagnosis, and a tailored therapeutic approach, including surgical removal and antiparasitic treatment, are crucial for successful management and improved long-term outcomes.\u003c/p\u003e","manuscriptTitle":"Isolated hydatid cyst in the medial rectus muscle: unveiling a rare orbital occurrence","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-08-18 23:11:42","doi":"10.21203/rs.3.rs-4752323/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-08-06T14:01:44+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-08-02T16:49:38+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-07-30T06:37:40+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-07-24T16:25:19+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"84886127720937327747560772763576318626","date":"2024-07-24T16:08:11+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"277394453594693633452354731282517883282","date":"2024-07-24T06:39:29+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"304864723948026813609654826084136776057","date":"2024-07-23T21:04:53+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"217653883611197882745457384258542974834","date":"2024-07-22T18:03:14+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"155180200192227827041004150138320828924","date":"2024-07-22T18:02:37+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"131187485771387554840130695297108651250","date":"2024-07-22T12:35:25+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"138701781329033302267674668491424629965","date":"2024-07-22T12:20:51+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-07-22T08:31:04+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-07-17T07:48:50+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-07-17T07:48:41+00:00","index":"","fulltext":""},{"type":"submitted","content":"Journal of Ophthalmic Inflammation and Infection","date":"2024-07-16T20:55:29+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"journal-of-ophthalmic-inflammation-and-infection","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"joii","sideBox":"Learn more about [Journal of Ophthalmic Inflammation and Infection](http://joii-journal.springeropen.com)","snPcode":"12348","submissionUrl":"https://submission.nature.com/new-submission/12348/3","title":"Journal of Ophthalmic Inflammation and Infection","twitterHandle":"@SpringerOpen","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"7cbc0c96-664f-4724-a129-21f21581c838","owner":[],"postedDate":"August 18th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2024-11-18T16:00:10+00:00","versionOfRecord":{"articleIdentity":"rs-4752323","link":"https://doi.org/10.1186/s12348-024-00436-8","journal":{"identity":"journal-of-ophthalmic-inflammation-and-infection","isVorOnly":false,"title":"Journal of Ophthalmic Inflammation and Infection"},"publishedOn":"2024-11-12 15:57:06","publishedOnDateReadable":"November 12th, 2024"},"versionCreatedAt":"2024-08-18 23:11:42","video":"","vorDoi":"10.1186/s12348-024-00436-8","vorDoiUrl":"https://doi.org/10.1186/s12348-024-00436-8","workflowStages":[]},"version":"v1","identity":"rs-4752323","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4752323","identity":"rs-4752323","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}