Fig. 3.

Pathological findings of the lung biopsy. Atypical large-sized lymphoid cells filled several distended vessels beneath the pleura and in the pulmonary parenchyma (hematoxylin and eosin; × 400 (A)). The neoplastic cells had irregular nuclear contours, prominent nucleoli, and narrow cytoplasm (black arrow), described in a partially expanded image on the lower right field. Abnormal mitosis was prominent in the cells. The moderate inflammatory response caused mainly by plasma cells was seen in perivascular areas, but no fibrin thrombi or necrosis was observed. The alveolar epithelial cells showed reactive nuclear enlargement. The tumor cells in pulmonary arterioles were positive for cytoplasmic CD3 (B), CD56 (C), perforin, and Ki-96 (not shown). In situ hybridization analysis for Epstein-Barr virus-encoded messenger RNA was positive (D).