Malignant Triton tumor of the retroperitoneum: a case report about a rare diagnostic trap and a geriatric challenge

Malignant Triton tumor of the retroperitoneum: a case report about a rare diagnostic trap and a geriatric challenge | 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 Malignant Triton tumor of the retroperitoneum: a case report about a rare diagnostic trap and a geriatric challenge Guillaume SAUVINET, Khalid ALGHAMDI, Noëlle WEINGERTNER, Louise SCHEER, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4343602/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background: Malignant Triton Tumor (MTT) constitutes a subtype of Malignant Peripheral Nerve Sheath Tumor, whose retroperitoneal localization is extremely rare: at this time, only some twenty cases reports have been reported since its first description. We present the case of a MTT diagnosed on the histological examination after the mass resection, which was previously considered as myxofibrosarcoma according to biopsy findings. Case presentation: A 76-year-old woman suffered from femoral pains resulting from a left retroperitoneal mass, 33cm in diameter, arising from the major psoas muscle. In view of the so-called diagnosis and the age, we decided to perform an up-front R1 left compartmentectomy sparing pancreas without neoadjuvant treatment. The tumor was found to involve the femoral trunk nerve, necessitating its resection so that the piece remains unfragmented. Immunohistochemical analysis finally revealed a MTT with a focal positivity for S100, as well as a focal staining with markers of skeletal muscle differentiation. The postoperative course was uneventful besides the foreseeable femoral paralysis, and adjuvant irradiation was proposed. Tumor heterogeneity can explain the discrepancy between the settings of the core needle biopsy and the definitive histological conclusions, and highlights the difficulty bringing the correct diagnosis with a biopsy alone. Nevertheless, according to the acknowledged poor prognosis, the risk-benefit balance in this particular context should have discouraged a wider resection even if MTT was diagnosed before surgery. Conclusions: This case report raises the question of the major place of geriatric preoperative assessment and the appropriateness of multi-organs removals in elder patients, more specifically in those presenting aggressive sarcomas such as MTT. Malignant Triton Tumor Malignant Peripheral Nerve Sheath Tumor soft tissue sarcoma retroperitoneum compartmentectomy geriatric assessment Figures Figure 1 Figure 2 Figure 3 BACKGROUND Malignant Triton Tumor (MTT) is a rare soft-tissue sarcoma (STS) which belongs to the heterogeneous group of the Malignant Peripheral Nerve Sheath Tumors (MPNSTs). Masson described it in 1932 ( 1 ). MPNST originates from Schwann cells and neural crest, whereas the MTT differs by a focal rhabdomyoblastic differentiation ( 2 ). It received its name “Triton” from the experimentation of Locatelli ( 3 ) who succeed in growing a supernumerary limb on Triton salamander’s backs after a peripheral nerve graft. There is a relationship of MPNST with Von Recklinghausen’s disease (4;5) namely Neurofibromatosis type 1 (NF1). Extremities, neck and head constitute the usual locations ( 6 ). In contrast, retroperitoneum remains an extremely rare site: to date, only some twenty cases of retroperitoneal MTT have been reported ( 7 ). According to Brooks and Yakulis about this subtype of MPNSTs, there is a logic trend in favor of the complete resection, associated with an improved prognosis and decreased risk of local and distant relapse (6;8). We present the case of a patient with a retroperitoneal mass initially diagnosed as myxofibrosarcoma based on biopsy findings. However, subsequent immunohistochemical analysis following surgical resection revealed MTT. CASE PRESENTATION A 76-year-old woman, with diabetes mellitus but without a history of NF1, was admitted to our surgical department due to the radiologic discovery of a left retroperitoneal mass in the context of intractable neuropathic femoral pains on the ipsilateral side. Contrast-enhanced computed tomography (CT) showed a heterogeneous tissue tumor (Fig. 1 ), 33cm in diameter, encompassing the left psoas major muscle and compressing the kidney, the pancreas tail and the colon. At this time, there was no evidence that the mass arose from a nerve trunk. Positron emission tomography (PET) scan did not displayed suspect lymphadenopathy or distant metastasis. Core needle biopsy of the tumor was performed and analyzed by a pathologist expert in soft tissue pathology. It demonstrated a malignant spindle cell proliferation in a myxoid background, without any line of differentiation after extensive immunohistochemical analysis, and without MDM2 gene amplification by FISH (fluorescence in situ hybridization), favoring a diagnosis of a possible myxofibrosarcoma. Considering the patient’s age, the disabling symptoms and the tumor size, we proposed to perform an up-front R1-resection without neoadjuvant treatment to ease the patient as soon as possible while minimizing operative morbidity and preserving the femoral nerve whenever feasible. The regional Sarcomas multidisciplinary committee approved this therapeutic option and the patient accepted it. After a prehabilitation by a nutritional optimization and an oncogeriatric assessment, she underwent a left compartmentectomy sparing the pancreas tail, taking away en bloc the left colon, the kidney with the adrenal gland, and the whole major psoas muscle belly (Fig. 2 ). The tumor was found to clearly involve the femoral nerve, necessitating its resection despite the inevitable loss of function. We performed a colorectal Knight-Griffen anastomosis to restore continuity, without requiring a diverting stoma in view of the favorable clinical and operative conditions. The resection was macroscopically complete and the mass unfragmented. The postoperative course was uneventful except temporary uncontrolled diabetes and foreseeable left femoral paralysis. The patient was discharged on day 12 and admitted to a rehabilitation center. Macroscopic examination of the resection specimen displayed a quite well delineated mass, with fibrous and myxoid areas. This specimen was extensively sampled. Histopathological examination (Fig. 3 ) showed a spindle cell and pleomorphic sarcomatous proliferation, quite heterogeneous, with hypercellular atypical and mitotically active areas (more than 15 mitoses/mm2) alternating with hypocellular less atypical often myxoid ones, the latter resembling the proliferation seen on core needle biopsy. Necrosis involved less than 50% of the tumor. Moreover, macroscopic and microscopic examination clearly demonstrated the intimal relationship of the tumor with nervous structures of the femoral nerve. Immunohistochemical analysis was performed and revealed a focal positivity of the tumor cells for S100, as well as a focal staining with markers of skeletal muscle differentiation, namely desmin, Myogenin and MyoD1. Pathological features of this resection specimen was then in favor of a MPNST, high grade, with skeletal muscle differentiation, leading to the diagnosis of MTT. The surgical resection was marginal, in coherence with the R1 preoperative intention. Sarcomas multidisciplinary committee proposed an adjuvant irradiation, performed two months later after a new contrast-enhanced CT. DISCUSSION AND CONCLUSIONS According to the WHO Classification of soft tissue tumors ( 9 ), MPNST is a sarcoma arising from a peripheral nerve ( 10 ), a pre-existing benign nerve sheath tumor, or in a patient affected by NF1. In the absence of these settings, the diagnosis can be based on the histological and immunohistochemical features suggesting Schwannian differentiation (S100 and/or SOX10 positivity). It is however important to underline that S100 and SOX10 immunohistochemical positivity is usually patchy or focal in MPNST, and can be totally absent, causing diagnostic difficulties. Besides, MPNST harbor heterologous elements in approximately 15% of cases, namely skeletal muscle, cartilage, bone, vascular and even glandular differentiation. Heterologous differentiation in a sarcoma should suggest an MPNST. Discrepancy between the diagnosis proposed after pathological analysis of the core needle biopsy and the resection specimen is clearly explained by the tumor heterogeneity, with a total absence of immunohistochemical differentiation of the tumor cells represented on the biopsy sample. Our case report highlights the significant and inevitable risk of misdiagnosis on microbiopsy due to tumoral heterogeneity, in spite of proofreading recommended by the French Sarcoma Group. Nevertheless, diagnosis of the MTT in this particular case probably should have not modified the patient care, especially concerning the surgical margins and the range of the intended resection. Enneking et al. had described four types of histologically margins since 1980 for musculoskeletal sarcomas but more generally for all types of sarcomas: intralesional, marginal, wide and radical, these two last steps remaining not clearly distinguished ( 11 ). Nowadays, we are rather used to employing terms as R0 or R1 resection that locate the lesion border more or less than one millimeter from the surgical section, keeping in mind that R2 resection is considered as intralesional and thus judged during the operative procedure ( 12 ). As Liu et al. highlighted, anatomic constraints in the retroperitoneal space make significantly difficult large complete excisions R0 avoiding multiples organs resections and major morbidity, the completeness remaining the challenging aim for the surgeon ( 7 ). For these reasons, it is important to carefully evaluate the risk-benefit surgical balance for the elder patients, for whom quality of life could be more essential than disease-free survival (DFS). A systematic oncogeriatric consultation is therefore proposed to them before any oncologic treatment, whether for irradiation, chemotherapy and/or surgery. Oncogeriatric evaluation allows exploration of multiple domains through assessment tools, to consider the elderly person as a whole. The elderly population is highly heterogeneous, and this assessment helps identify potential frailties, unknown geriatric issues, or unfavorable conditions that may increase treatment toxicity. It can also reveal factors that may complicate management. The assessment leads to personalized geriatric recommendations to optimize treatment ( 13 ). This precautionary approach is all the more important since MTT prognosis is very poor, with a 5-year survival rate of only 26% ( 8 ). According to the patients’ series of Terzic et al. ( 14 ), different clinical and histological prognostic parameters were identified: tumor location, tumor size, degree of differentiation, surgical margins and mitotic index, with a special attention paid to complete radical removal, significantly improving survival. In contrast, adjuvant treatment like irradiation or chemotherapy did not appear to better outcomes. In our case report, achieving wide margins (R0) would have required additional resections such as a pancreatectomy, and the excision of parietal muscles and aorta adventitia, which is clearly unreasonable, especially considering the prognosis, as they would not have resulted in a meaningful change in survival. This case of retroperitoneal MTT discovered after histological analysis shows the difficulty concluding a rare diagnosis with a core needle biopsy alone, and raises the question of the appropriateness of extensive surgical resections in elder patients, more specifically for aggressive tumors. Abbreviations MTT Malignant Triton tumor MPNST Malignant peripheral nerve sheath tumor STS Soft-tissue sarcoma CT Contrast-enhanced computed tomography PET Positron emission tomography FISH Fluorescence in situ hybridization Declarations Consent to participate and for publication We obtained the patient’s written informed consent. Ethics approval and consent to participate All procedures and examinations were performed in accordance with the ethical standards of the institutional research committee, and with the 1964 Helsinki declaration and its later amendments. Availability of data and materials The datasets used and analyzed during the current study are available from the corresponding author on reasonable request. Competing interests The authors declare that they have not competing interests. Funding No funding reported for data collection, decision to publish or preparation of the manuscript. Authors’ contributions GS operated on the patient and was a major contributor in writing the manuscript. KA operated on the patient and improved English language. NW performed the histological examination of the specimen and complemented the manuscript. LS performed the geriatric assessment and complemented the manuscript. ET analyzed CT data and performed X-ray reconstructions. DH performed the geriatric assessment. CB annotated the manuscript. Acknowledgements No applicable. References Masson P. Recklinghausen's Neurofibromatosis. Sensory Neuromas and Motor Neuromas. Libman anniversary 2, 1932: 798–802. Brunet A, Hermeziu O, Luciani A, Ortonne N. Tumeur Triton maligne : à propos d’un cas [Malignant Triton tumour: A case report]. Ann Pathol. 2021;41(3):317–22. French. Locatelli P. Formation de membres surnuméraires. CR Assoc Anat. 1925;20:279–82. Ducatman BS, Scheithauer BW, Piepgras DG, Reiman HM, Ilstrup DM. Malignant peripheral nerve sheath tumors. A clinicopathologic study of 120 cases. Cancer. 1986;57(10):2006–21. Jaing TH, Chuang CC, Jung SM, Wu CT, Tseng CK, Chen CS. Malignant triton tumor of the cervical spine: report of one case and review of the literature. Pediatr Neonatol. 2015;56(1):58–61. Brooks JS, Freeman M, Enterline HT. Malignant Triton tumors. Natural history and immunohistochemistry of nine new cases with literature review. Cancer. 1985;55(11):2543–9. Liu M, Bian J. Malignant Triton tumor of the retroperitoneum in a male unaffected by neurofibromatosis 1: A case report and literature review. Asian J Surg. 2022;45(12):2766–8. Yakulis R, Manack L, Murphy AI Jr.. Postradiation malignant triton tumor. A case report and review of the literature. Arch Pathol Lab Med. 1996;120(6):541–8. WHO Classification of Tumours. 5th Edition, Volume 3: Soft Tissue and Bone Tumours. Sbaraglia M, Bellan E, Dei Tos AP. The 2020 WHO Classification of Soft Tissue Tumours: news and perspectives. Pathologica. 2021;113(2):70–84. Enneking WF, Spanier SS, Goodman MA. A system for the surgical staging of musculoskeletal sarcoma. Clin Orthop Relat Res. 1980 Nov-Dec;(153):106–20. Wittekind C, Compton CC, Greene FL, Sobin LH. TNM residual tumor classification revisited. Cancer. 2002;94(9):2511–6. Wildiers H, Heeren P, Puts M, et al. International Society of Geriatric Oncology consensus on geriatric assessment in older patients with cancer. J Clin Oncol. 2014;32:2595–603. Terzic A, Bode B, Gratz KW, Stoeckli SJ. Prognostic factors for the malignant triton tumor of the head and neck. Head Neck. 2009;31(5):679–88. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted 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-4343602","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Case Report","associatedPublications":[],"authors":[{"id":299293423,"identity":"3afed585-2f81-42af-958a-7933b77bfe19","order_by":0,"name":"Guillaume 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14:39:33","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4343602/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4343602/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":56101263,"identity":"6f062626-2133-45cf-a68c-b65dacfbd011","added_by":"auto","created_at":"2024-05-08 14:39:27","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":251380,"visible":true,"origin":"","legend":"\u003cp\u003eAbdominal and pelvic contrast-enhanced computed tomography (CT) exhibited a large necrotic irregular mass.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-4343602/v1/3d2571c5f403062afb087e99.png"},{"id":56101262,"identity":"6d5d4f09-851f-41a2-ac54-12e2e0be7f1d","added_by":"auto","created_at":"2024-05-08 14:39:27","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":835552,"visible":true,"origin":"","legend":"\u003cp\u003eThe tumor bordered aorta (Ao), encompassed the major psoas muscle and involved the femoral nerve.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-4343602/v1/b7419c0d941647c9c2d3eb6e.png"},{"id":56101265,"identity":"9b72b758-5d2b-4603-85da-3bf1bb210774","added_by":"auto","created_at":"2024-05-08 14:39:27","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":1672606,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003e3a\u003c/strong\u003e: Histological aspect of the core needle biopsy, suggesting a myxofibrosarcoma.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3b\u003c/strong\u003e: Histological aspect of the resection specimen, with myxoid low cellular areas (right) alternating with high grade densely cellular areas (left)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3c\u003c/strong\u003e: The tumor appears in close proximity with nervous structures (top left).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3d\u003c/strong\u003e: On the resection specimen, tumor cells expressed focally MyoD1.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3e\u003c/strong\u003e: Immunohistochemical expression of S100 protein in seen on very rare tumor cells.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-4343602/v1/55c689928c56170f792fccb7.png"},{"id":69495229,"identity":"a43fb9b4-86c6-48f1-be15-06d8444b469c","added_by":"auto","created_at":"2024-11-21 03:47:10","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2796630,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4343602/v1/a796b35e-f250-44c6-b33c-f701f1fb7e90.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Malignant Triton tumor of the retroperitoneum: a case report about a rare diagnostic trap and a geriatric challenge","fulltext":[{"header":"BACKGROUND","content":"\u003cp\u003eMalignant Triton Tumor (MTT) is a rare soft-tissue sarcoma (STS) which belongs to the heterogeneous group of the Malignant Peripheral Nerve Sheath Tumors (MPNSTs). Masson described it in 1932 (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e). MPNST originates from Schwann cells and neural crest, whereas the MTT differs by a focal rhabdomyoblastic differentiation (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). It received its name \u0026ldquo;Triton\u0026rdquo; from the experimentation of Locatelli (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e) who succeed in growing a supernumerary limb on Triton salamander\u0026rsquo;s backs after a peripheral nerve graft. There is a relationship of MPNST with Von Recklinghausen\u0026rsquo;s disease (4;5) namely Neurofibromatosis type 1 (NF1). Extremities, neck and head constitute the usual locations (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e). In contrast, retroperitoneum remains an extremely rare site: to date, only some twenty cases of retroperitoneal MTT have been reported (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e). According to Brooks and Yakulis about this subtype of MPNSTs, there is a logic trend in favor of the complete resection, associated with an improved prognosis and decreased risk of local and distant relapse (6;8).\u003c/p\u003e \u003cp\u003eWe present the case of a patient with a retroperitoneal mass initially diagnosed as myxofibrosarcoma based on biopsy findings. However, subsequent immunohistochemical analysis following surgical resection revealed MTT.\u003c/p\u003e"},{"header":"CASE PRESENTATION","content":"\u003cp\u003eA 76-year-old woman, with diabetes mellitus but without a history of NF1, was admitted to our surgical department due to the radiologic discovery of a left retroperitoneal mass in the context of intractable neuropathic femoral pains on the ipsilateral side. Contrast-enhanced computed tomography (CT) showed a heterogeneous tissue tumor (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e), 33cm in diameter, encompassing the left psoas major muscle and compressing the kidney, the pancreas tail and the colon. At this time, there was no evidence that the mass arose from a nerve trunk. Positron emission tomography (PET) scan did not displayed suspect lymphadenopathy or distant metastasis.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eCore needle biopsy of the tumor was performed and analyzed by a pathologist expert in soft tissue pathology. It demonstrated a malignant spindle cell proliferation in a myxoid background, without any line of differentiation after extensive immunohistochemical analysis, and without MDM2 gene amplification by FISH (fluorescence in situ hybridization), favoring a diagnosis of a possible myxofibrosarcoma.\u003c/p\u003e \u003cp\u003eConsidering the patient\u0026rsquo;s age, the disabling symptoms and the tumor size, we proposed to perform an up-front R1-resection without neoadjuvant treatment to ease the patient as soon as possible while minimizing operative morbidity and preserving the femoral nerve whenever feasible. The regional Sarcomas multidisciplinary committee approved this therapeutic option and the patient accepted it. After a prehabilitation by a nutritional optimization and an oncogeriatric assessment, she underwent a left compartmentectomy sparing the pancreas tail, taking away en bloc the left colon, the kidney with the adrenal gland, and the whole major psoas muscle belly (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). The tumor was found to clearly involve the femoral nerve, necessitating its resection despite the inevitable loss of function. We performed a colorectal Knight-Griffen anastomosis to restore continuity, without requiring a diverting stoma in view of the favorable clinical and operative conditions. The resection was macroscopically complete and the mass unfragmented. The postoperative course was uneventful except temporary uncontrolled diabetes and foreseeable left femoral paralysis. The patient was discharged on day 12 and admitted to a rehabilitation center.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eMacroscopic examination of the resection specimen displayed a quite well delineated mass, with fibrous and myxoid areas. This specimen was extensively sampled. Histopathological examination (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e) showed a spindle cell and pleomorphic sarcomatous proliferation, quite heterogeneous, with hypercellular atypical and mitotically active areas (more than 15 mitoses/mm2) alternating with hypocellular less atypical often myxoid ones, the latter resembling the proliferation seen on core needle biopsy. Necrosis involved less than 50% of the tumor. Moreover, macroscopic and microscopic examination clearly demonstrated the intimal relationship of the tumor with nervous structures of the femoral nerve. Immunohistochemical analysis was performed and revealed a focal positivity of the tumor cells for S100, as well as a focal staining with markers of skeletal muscle differentiation, namely desmin, Myogenin and MyoD1. Pathological features of this resection specimen was then in favor of a MPNST, high grade, with skeletal muscle differentiation, leading to the diagnosis of MTT. The surgical resection was marginal, in coherence with the R1 preoperative intention.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eSarcomas multidisciplinary committee proposed an adjuvant irradiation, performed two months later after a new contrast-enhanced CT.\u003c/p\u003e"},{"header":"DISCUSSION AND CONCLUSIONS","content":"\u003cp\u003eAccording to the WHO Classification of soft tissue tumors (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e), MPNST is a sarcoma arising from a peripheral nerve (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e), a pre-existing benign nerve sheath tumor, or in a patient affected by NF1. In the absence of these settings, the diagnosis can be based on the histological and immunohistochemical features suggesting Schwannian differentiation (S100 and/or SOX10 positivity). It is however important to underline that S100 and SOX10 immunohistochemical positivity is usually patchy or focal in MPNST, and can be totally absent, causing diagnostic difficulties. Besides, MPNST harbor heterologous elements in approximately 15% of cases, namely skeletal muscle, cartilage, bone, vascular and even glandular differentiation. Heterologous differentiation in a sarcoma should suggest an MPNST.\u003c/p\u003e \u003cp\u003eDiscrepancy between the diagnosis proposed after pathological analysis of the core needle biopsy and the resection specimen is clearly explained by the tumor heterogeneity, with a total absence of immunohistochemical differentiation of the tumor cells represented on the biopsy sample. Our case report highlights the significant and inevitable risk of misdiagnosis on microbiopsy due to tumoral heterogeneity, in spite of proofreading recommended by the French Sarcoma Group.\u003c/p\u003e \u003cp\u003eNevertheless, diagnosis of the MTT in this particular case probably should have not modified the patient care, especially concerning the surgical margins and the range of the intended resection. Enneking et al. had described four types of histologically margins since 1980 for musculoskeletal sarcomas but more generally for all types of sarcomas: intralesional, marginal, wide and radical, these two last steps remaining not clearly distinguished (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e). Nowadays, we are rather used to employing terms as R0 or R1 resection that locate the lesion border more or less than one millimeter from the surgical section, keeping in mind that R2 resection is considered as intralesional and thus judged during the operative procedure (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e). As Liu et al. highlighted, anatomic constraints in the retroperitoneal space make significantly difficult large complete excisions R0 avoiding multiples organs resections and major morbidity, the completeness remaining the challenging aim for the surgeon (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e). For these reasons, it is important to carefully evaluate the risk-benefit surgical balance for the elder patients, for whom quality of life could be more essential than disease-free survival (DFS). A systematic oncogeriatric consultation is therefore proposed to them before any oncologic treatment, whether for irradiation, chemotherapy and/or surgery. Oncogeriatric evaluation allows exploration of multiple domains through assessment tools, to consider the elderly person as a whole. The elderly population is highly heterogeneous, and this assessment helps identify potential frailties, unknown geriatric issues, or unfavorable conditions that may increase treatment toxicity. It can also reveal factors that may complicate management. The assessment leads to personalized geriatric recommendations to optimize treatment (\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThis precautionary approach is all the more important since MTT prognosis is very poor, with a 5-year survival rate of only 26% (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e). According to the patients\u0026rsquo; series of Terzic et al. (\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e), different clinical and histological prognostic parameters were identified: tumor location, tumor size, degree of differentiation, surgical margins and mitotic index, with a special attention paid to complete radical removal, significantly improving survival. In contrast, adjuvant treatment like irradiation or chemotherapy did not appear to better outcomes. In our case report, achieving wide margins (R0) would have required additional resections such as a pancreatectomy, and the excision of parietal muscles and aorta adventitia, which is clearly unreasonable, especially considering the prognosis, as they would not have resulted in a meaningful change in survival.\u003c/p\u003e \u003cp\u003eThis case of retroperitoneal MTT discovered after histological analysis shows the difficulty concluding a rare diagnosis with a core needle biopsy alone, and raises the question of the appropriateness of extensive surgical resections in elder patients, more specifically for aggressive tumors.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eMTT\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eMalignant Triton tumor\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eMPNST\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eMalignant peripheral nerve sheath tumor\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eSTS\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eSoft-tissue sarcoma\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eCT\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eContrast-enhanced computed tomography\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003ePET\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003ePositron emission tomography\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eFISH\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eFluorescence in situ hybridization\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eConsent to participate and for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe obtained the patient\u0026rsquo;s written informed consent.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll procedures and examinations were performed in accordance with the ethical standards of the institutional research committee, and with the 1964 Helsinki declaration and its later amendments.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have not competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo funding reported for data collection, decision to publish or preparation of the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026rsquo; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eGS operated on the patient and was a major contributor in writing the manuscript.\u003c/p\u003e\n\u003cp\u003eKA operated on the patient and improved English language.\u003c/p\u003e\n\u003cp\u003eNW performed the histological examination of the specimen and complemented the manuscript.\u003c/p\u003e\n\u003cp\u003eLS performed the geriatric assessment and complemented the manuscript.\u003c/p\u003e\n\u003cp\u003eET analyzed CT data and performed X-ray reconstructions.\u003c/p\u003e\n\u003cp\u003eDH performed the geriatric assessment.\u003c/p\u003e\n\u003cp\u003eCB annotated the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo applicable.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eMasson P. Recklinghausen's Neurofibromatosis. Sensory Neuromas and Motor Neuromas. Libman anniversary 2, 1932: 798\u0026ndash;802.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBrunet A, Hermeziu O, Luciani A, Ortonne N. Tumeur Triton maligne : \u0026agrave; propos d\u0026rsquo;un cas [Malignant Triton tumour: A case report]. Ann Pathol. 2021;41(3):317\u0026ndash;22. French.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLocatelli P. Formation de membres surnum\u0026eacute;raires. CR Assoc Anat. 1925;20:279\u0026ndash;82.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDucatman BS, Scheithauer BW, Piepgras DG, Reiman HM, Ilstrup DM. Malignant peripheral nerve sheath tumors. A clinicopathologic study of 120 cases. Cancer. 1986;57(10):2006\u0026ndash;21.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJaing TH, Chuang CC, Jung SM, Wu CT, Tseng CK, Chen CS. Malignant triton tumor of the cervical spine: report of one case and review of the literature. Pediatr Neonatol. 2015;56(1):58\u0026ndash;61.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBrooks JS, Freeman M, Enterline HT. Malignant Triton tumors. Natural history and immunohistochemistry of nine new cases with literature review. Cancer. 1985;55(11):2543\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiu M, Bian J. Malignant Triton tumor of the retroperitoneum in a male unaffected by neurofibromatosis 1: A case report and literature review. Asian J Surg. 2022;45(12):2766\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYakulis R, Manack L, Murphy AI Jr.. Postradiation malignant triton tumor. A case report and review of the literature. Arch Pathol Lab Med. 1996;120(6):541\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWHO Classification of Tumours. 5th Edition, Volume 3: Soft Tissue and Bone Tumours.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSbaraglia M, Bellan E, Dei Tos AP. The 2020 WHO Classification of Soft Tissue Tumours: news and perspectives. Pathologica. 2021;113(2):70\u0026ndash;84.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eEnneking WF, Spanier SS, Goodman MA. A system for the surgical staging of musculoskeletal sarcoma. Clin Orthop Relat Res. 1980 Nov-Dec;(153):106\u0026ndash;20.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWittekind C, Compton CC, Greene FL, Sobin LH. TNM residual tumor classification revisited. Cancer. 2002;94(9):2511\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWildiers H, Heeren P, Puts M, et al. International Society of Geriatric Oncology consensus on geriatric assessment in older patients with cancer. J Clin Oncol. 2014;32:2595\u0026ndash;603.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTerzic A, Bode B, Gratz KW, Stoeckli SJ. Prognostic factors for the malignant triton tumor of the head and neck. Head Neck. 2009;31(5):679\u0026ndash;88.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Malignant Triton Tumor, Malignant Peripheral Nerve Sheath Tumor, soft tissue sarcoma, retroperitoneum, compartmentectomy, geriatric assessment","lastPublishedDoi":"10.21203/rs.3.rs-4343602/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4343602/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground:\u003c/strong\u003e Malignant Triton Tumor (MTT) constitutes a subtype of Malignant Peripheral Nerve Sheath Tumor, whose retroperitoneal localization is extremely rare: at this time, only some twenty cases reports have been reported since its first description. We present the case of a MTT diagnosed on the histological examination after the mass resection, which was previously considered as myxofibrosarcoma according to biopsy findings.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCase presentation:\u003c/strong\u003e A 76-year-old woman suffered from femoral pains resulting from a left retroperitoneal mass, 33cm in diameter, arising from the major psoas muscle. In view of the so-called diagnosis and the age, we decided to perform an up-front R1 left compartmentectomy sparing pancreas without neoadjuvant treatment. The tumor was found to involve the femoral trunk nerve, necessitating its resection so that the piece remains unfragmented. Immunohistochemical analysis finally revealed a MTT with a focal positivity for S100, as well as a focal staining with markers of skeletal muscle differentiation. The postoperative course was uneventful besides the foreseeable femoral paralysis, and adjuvant irradiation was proposed.\u003c/p\u003e\n\u003cp\u003eTumor heterogeneity can explain the discrepancy between the settings of the core needle biopsy and the definitive histological conclusions, and highlights the difficulty bringing the correct diagnosis with a biopsy alone. Nevertheless, according to the acknowledged poor prognosis, the risk-benefit balance in this particular context should have discouraged a wider resection even if MTT was diagnosed before surgery.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions:\u003c/strong\u003e This case report raises the question of the major place of geriatric preoperative assessment and the appropriateness of multi-organs removals in elder patients, more specifically in those presenting aggressive sarcomas such as MTT.\u003c/p\u003e","manuscriptTitle":"Malignant Triton tumor of the retroperitoneum: a case report about a rare diagnostic trap and a geriatric challenge","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-05-08 14:39:22","doi":"10.21203/rs.3.rs-4343602/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"ec0d1179-5436-4a49-a3ba-6ad3bc0f4d83","owner":[],"postedDate":"May 8th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-11-21T03:38:50+00:00","versionOfRecord":[],"versionCreatedAt":"2024-05-08 14:39:22","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4343602","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4343602","identity":"rs-4343602","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}