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Primary cutaneous synovial sarcoma—Sometimes the hoof beats are zebras
Author(s) -
Sharma Anurag,
Ko Jennifer Susan,
Billings Steven D.
Publication year - 2021
Publication title -
journal of cutaneous pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.597
H-Index - 75
eISSN - 1600-0560
pISSN - 0303-6987
DOI - 10.1111/cup.13766
Subject(s) - synovial sarcoma , pathology , sarcoma , differential diagnosis , cytokeratin , hemangiopericytoma , soft tissue , scalp , medicine , anatomy , clear cell sarcoma , cd34 , nodule (geology) , biology , immunohistochemistry , stem cell , paleontology , genetics
Synovial sarcoma accounts for 5% to 10% of soft tissue sarcoma and it typically presents as a deep soft tissue mass. Primary cutaneous presentation is exceptionally rare, with only isolated case reports. We report a case of primary cutaneous synovial sarcoma in a 58‐year‐old woman that presented as a nodule involving the left occipital scalp. A complete radiologic evaluation of the patient failed to reveal any other mass lesion. Histologic sections showed a densely cellular, diffuse spindle cell proliferation within the subcutis. The lesion was composed of uniform, plump spindled cells with nuclei and vesicular chromatin, arranged in haphazard fascicles. There was admixed hemorrhage and a hemangiopericytoma‐like vasculature. Immunohistochemically, the spindled cells showed focal strong positivity for cytokeratin (CK) OSCAR, CK5/6, CK34BE12, and pan‐CK. Fluorescence in situ hybridization was positive for a rearrangement of SYT (SS18) , confirming the diagnosis of monophasic synovial sarcoma. Synovial sarcoma should be considered in the differential diagnosis of monomorphous spindle cell tumors, especially if the tumors have a hemangiopericytoma‐like vasculature or express keratins. In such cases, confirmatory molecular testing should be performed to confirm the diagnosis.