We report a case of a 67-year-old male patient with a sinonasal tumor that showed areas of classic biphenotypic sinonasal sarcoma (BSNS) which in some sections sharply transitioned into high-grade rhabdomyosarcoma. Immunohistochemically, the conventional BSNS parts showed S100 protein, SMA, PAX7, and focal MyoD1 expression, whereas desmin and myogenin were negative. In contrast, the cells in high-grade areas expressed desmin, MyoD1, myogenin, and PAX7, while being negative for S100 protein and SMA. Using the Archer FusionPlex assay, the classical PAX3::MAML3 gene fusion was detected. FISH for PAX3 and MAML3 confirmed a break of these genes in both components. Despite aggressive therapy, the tumor progression resulted in the patient's death. The herein presented case, together with 2 previously published cases of BSNS with high-grade transformation, helps to better understand this novel phenomenon. Although the risk for such transformation appears low, it has important clinical and diagnostic implications which are discussed.

• MeSH
• alveolární rhabdomyosarkom * MeSH
• desmin MeSH
• imunohistochemie MeSH
• lidé středního věku MeSH
• lidé MeSH
• myogenin MeSH
• nádorové biomarkery genetika   MeSH
• nádory měkkých tkání * genetika   MeSH
• nádory vedlejších dutin nosních * patologie   MeSH
• proteiny S100 MeSH
• rhabdomyosarkom * genetika   MeSH
• sarkom * genetika   MeSH
• trans-aktivátory MeSH
• transkripční faktor PAX3 genetika   MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• kazuistiky MeSH

Biphenotypic sinonasal sarcoma (BSNS) is a recently recognized type of sarcoma arising exclusively in the sinonasal tract displaying unique clinical course, histopathology, and genetics. Due to its rarity, only case series and case reports are available. In order to provide an overview of the current understanding of this disease, we present a comprehensive review of the literature and present three previously unreported cases of BSNS. A total of 55 genetically characterized and 41 cases without molecular data were identified in the literature. Two-thirds of patients were female and the peak incidence was in the fifth decade. Fatal outcome was rare (two cases with intracranial extension) and local recurrence occurred in 31.6%, all occurring within 5 years after initial treatment. Histologically, BSNS is highly cellular in the majority of cases and composed of fascicles of spindle cells, with entrapped hyperplastic surface epithelium being a frequent finding. The immunohistochemical profile is characteristic due to the biphasic nature of this lesion, with shared features of both myogenic and neural origin. Rhabdomyoblastic differentiation is apparent in a subset of cases. The most common genetic event is the PAX3-MAML3 fusion (58.6%) but isolated PAX3 rearrangement (19.2%), absence of rearrangements (9.1%), PAX3-FOXO1 (8.1%), PAX3-NCOA1 (4%), and isolated MAML3 rearrangement (2%) have also been reported. In conclusion, the recognition of BSNS is crucial due to its relatively indolent clinical course. A selected immunohistochemical panel and/or molecular confirmation can be used to aid in appropriate diagnosis and consequently in prognostication and to avoid overtreatment with chemotherapy regimens used in its mimics.

• MeSH
• DNA vazebné proteiny genetika   MeSH
• dospělí MeSH
• fenotyp MeSH
• forkhead box protein O1 genetika   MeSH
• fúze genů MeSH
• fúzní onkogenní proteiny genetika   MeSH
• genová přestavba MeSH
• imunohistochemie MeSH
• jaderné proteiny genetika   MeSH
• koaktivátor 1 jaderných receptorů genetika   MeSH
• lidé středního věku MeSH
• lidé MeSH
• nádorové biomarkery genetika   MeSH
• nádory vedlejších dutin nosních diagnóza   genetika   patologie   MeSH
• prognóza MeSH
• sarkom diagnóza   genetika   patologie   MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• transkripční faktor PAX3 genetika   MeSH
• transkripční faktory paired box genetika   MeSH
• transkripční faktory genetika   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• kazuistiky MeSH
• přehledy MeSH