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

Abstract

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

Synovial sarcoma presenting as a lung mass and diagnosed by cytology

“…9,16 Our case was positive for CD99 and Bcl2, and negative for synaptophysin and chromogranin, which supports diagnosis of synovial sarcoma. Nuclear molding and crushing artifact are quite commonly seen in small cell carcinoma.…”

Cytological findings of monophasic synovial sarcoma presenting as a lung mass: report of a case and review of the literature

“…[1][2][3][4] There are a few case reports of synovial sarcoma diagnosed based on FNA biopsy. [5][6][7][8][9][10][11][12][13][14][15][16] The cases described involved widespread locations such as heart, thyroid, kidney, prostate, large vessels, parapharyngeal space, axilla, and lower extremity.…”

“…To our knowledge, there are only six cytology case reports of synovial sarcoma located in the lung/mediastinum. [5][6][7][8][9] The clinical presentation, radiological findings, cytological features, immunohistochemical profiles, and other ancillary studies are summarized in Table 1. It is more common in women (female = 4, male = 2).…”

Fine‐needle aspiration cytology of primary mediastinal synovial sarcoma: A case report with an immunocytochemical approach

“…3,5,6 The cytological features of SS have previously been reported 4,7 ; however, only one cytological report on primary mediastinal SS has been published. 8 Here, we present the first cytological report on primary mediastinal SS with an immunocytochemical analysis for TLE-1.…”