Caractérisation clinico-pathologique et moléculaire du sarcome sinonasal biphénotypique à partir d’une série de 41 cas

Abstract : Biphenotypic sinonasal sarcoma (BSNS) is a locally aggressive tumor occurring in the sinonasal region. This tumor harbors both myogenic and neural differentiation and is characterized by PAX3 rearrangement with MAML3 as the most frequent fusion partner, but the partner of PAX3 remains unidentified in a subset of cases. About 70 cases have been reported so far. In this study, we report a series of 41 cases with clinical, pathological and molecular description. Twenty-five (61%) patients were female and median age was 49 years. Tumors arose predominantly in the nasal cavity and ethmoidal sinuses. Local recurrences occurred in 8 cases out of 25 patients (32%). Histological features were characteristic of BSNS with 5 cases showing focal rhabdomyoblastic differentiation. Immunohistochemistry showed a constant positivity of S100 protein and PAX3 and negativity of SOX10. MyoD1 was focally positive in 91% of cases whereas only 20% were positive for myogenin. Molecular analysis showed a PAX3-MAML3 transcript in 37 cases (90%). RNA sequencing was performed in the 4 negative cases for PAX3-MAML3 fusion and showed that one case harbored a PAX3-FOXO1 fusion as previously described in the literature and 2 novel fusions: PAX3-WWTR1 fusion in 2 cases and PAX3-NCOA2 fusion in one case. RNA sequencing results were confirmed by FISH, RT-PCR and Sanger sequencing. The PAX3-NCOA2-positive case showed focal rhabdomyoblatic differentiation. In conclusion, we report 2 novel fusions (PAX3-WWTR1 and PAX3-NCOA2) in BSNS and show that MyoD1 is more sensitive than myogenin for demonstrating myogenic differentiation in this tumor.
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Master Thesis
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https://dumas.ccsd.cnrs.fr/dumas-02100130
Contributor : Bu Carreire Université de Bordeaux <>
Submitted on : Monday, April 15, 2019 - 3:43:23 PM
Last modification on : Thursday, June 27, 2019 - 1:31:46 AM

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Sophie Laffont. Caractérisation clinico-pathologique et moléculaire du sarcome sinonasal biphénotypique à partir d’une série de 41 cas. Médecine humaine et pathologie. 2019. ⟨dumas-02100130⟩

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