Fig. 3

Case 2: HE staining of needle biopsy specimen reveals that round or ovoid tumor cells with clear cytoplasm are arranged into nests (a, inset: low-power view of needle biopsy), and high-power view shows the epithelioid cells with moderate to marked cytological atypia (b). Resected specimens reveal that epithelioid tumor cells with sheet or nest-like distribution invade into the pulmonary tissues (c, left area), and multifocal coagulative necroses are seen (c), moderate and high-power view of which show the clear epithelioid tumor cells (d, e) with CD21 expression (f), similarly to those of core needle biopsy