June Case of the Month

Clinical History: Middle aged man with a large central lung tumor. Endobronchial biopsies demonstrate a poorly differentiated high grade neoplasm with abundant necrosis (Figures 1-2). The tumor is composed of round to oval discohesive cells with prominent nucleoli, abundant mitotic activity and a relatively monomorphic appearance (Figures 3-5). Numerous rhabdoid cells with distinctive eosinophilic cytoplasmic inclusions indenting eccentrically located nuclei are present (Figures 3-5). The neoplastic cells are negative for all cytokeratins including, 7, 5/6, AE1/AE3, OSCAR and cam 5.2. The cells are negative for neuroendocrine markers synaptophysin, chromogranin, and CD56. The cells are also negative for CD45, TTF-1, p40, NUT, SOX10, CD31 and desmin. The cells have intact expression of INI-1. The neoplastic cells demonstrate complete loss of BRG1 expression (Figure 6).

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