Primary pleuropulmonary synovial sarcoma diagnosed by fine needle aspiration with cytogenetic confirmation: a case report.

Background: Pleuropulmonary synovial sarcomas (PPSSs) are rare neoplasins that have been well described in recent years, although there are only very infrequent reports within the cytology literature. Such lesions present a diagnostic challenge on fine needle aspiration (ENA) due to several factors, particularly when the aspirate material displays monophasic, small cell or poorly differentiated morphology. Immunoperoxidase studies on cell block material and confirmation with molecular cytogenetics are important tools to establish the diagnosis and determine appropriate therapy. We report a case of PPSS in a 27-year-old man diagnosed by computed tomography (CT)-guided FNA with confirmation by conventional and molecular cytogenetics.

Case: A 27-year-old man presented with several rapidly enlarging, pleura-based masses following a several-month history of recurrent hemopneumothorax. Previous surgical pathology on decorticated pleura was interpreted as a reactive mesothelial proliferation at another institution. Upon referral, CT-guided transthoracic FNA was performed. Smears revealed a highly cellular, dispersed "small round blue cell" neoplasm in a hemorrhagic background. The cytomorphology, in conjunction with a select immunoperoxidase panel, was diagnostic of PPSS. Conventional and molecular cytogenetics subsequently provided confirmation of the diagnosis.

Conclusion: PPSSs are uncommon neoplasms seldom diagnosed by FNA, with only very rare reports in the cytology literature. Although their cytomorphology has been well described, monophasic tumors and other morphologic variants present a diagnostic challenge and may be difficult to discern from a variety of neoplastic and reactive/reparative processes. Emphasis should be placed upon securing material at the time of aspiration for immunoperoxidase studies (cell block or core biopsy). In equivocal cases, conventional and/or molecular cytogenetic studies may be needed.