2009 Volume 48 Issue 3 Pages 119-123
Background : Follicular dendritic cell (FDC) sarcoma, a rare neoplasm occurring nodally and extranodally, very rarely occurs as primary pulmonary sarcoma. We report imprint-cytology findings in such a case and discuss the difficulties of differential diagnosis.
Case : A 63-year-old Japanese woman with cough, sputum, and pneumonia was found in computed tomography (CT) to have a lower left hepatic-lobe mass 3 cm in diameter. Transbronchial endoscopy showed a polypoid left-lobe mass. Imprint-cytology smears from endoscopic biopsy showed a cohesive group of pleomorphic polygonal cells but few lymphocytes, suggesting possible poorly differentiated squamous cell carcinoma, which was excised. Microscopic examination showed the tumor to congist of oval to spindle-shaped cells in sheets and interlacing storiform fascicles. The excised specimen contained numerous small lymphocytes. Tumor cells showed widespread immunoreactivity to a CD21+CD35 cocktail and anti-FDC antibodies. These findings yielded a definitive diagnosis of FDC sarcoma.
Conclusions : A dual cell population of large tumor cells and a lymphoid component consisting mainly of lymphocytes and plasma cells is cytologically indicative of FDC sarcoma. Our case demonstrates, however, that FDC sarcoma should be included in a differential diagnosis of poorly differentiated lung cancer even in the absence of a dual cell population in cytological specimens.
