Fine needle aspiration of primary mediastinal synovial sarcoma: Cytomorphologic, immunohistochemical, and molecular study

摘要: The cytologic diagnosis of synovial sarcoma (SS) can be difficult when it occurs in unusual locations, atypical age groups, and/or have morphology. We report a case primary mediastinal SS 65-year-old male with long smoking history who presented increasing shortness breath and was found to 14.2 cm mass. Smears from the endobronchial ultrasound guided fine needle aspiration mass were moderately cellular consisting loosely cohesive clusters, some which demonstrated nuclear molding, dispersed single cells. relatively uniform tumor cells had high nuclear-to-cytoplasmic ratio, finely granular chromatin, inconspicuous nucleoli. Some spindled morphology unipolar wispy tails naked nuclei. Based on clinical presentation cytomorphologic features, our initial differential diagnoses included carcinoid, small cell carcinoma, basaloid squamous sarcoma, lymphoma. Immunohistochemical studies block sections revealed that focally positive for cytokeratin diffusely CD56, while negative CD45, synaptophysin chromogranin. Ultimately, an immunohistochemical stain TLE-1 strong positivity molecular showed presence t(X; 18) SYT/SSX1 translocation confirming SS. In this report, we describe features SS, its diagnostic pitfalls, potential mimics mediastinum.