Fig. 6: Immuonohistochemistry for SDHB.

Serial sections stained with hematoxylin and eosin (A, C) and SDHB IHC (B, D). Entrapped benign tubules were frequently seen at the edge of the tumors. SDHB IHC shows retained positive cytoplasmic staining in the internal controls (including entrapped benign tubules), but all the neoplastic cells are negative.