Fig. 2: Most of the tumors demonstrated the typical morphologic features of SDH-deficient RCC.

They were well circumscribed, sometimes with a pseudocapsule separating them from the adjacent non-neoplastic kidney (A). Entrapped non-neoplastic tubules or glomeruli were a frequent finding (B). In some cases, the cells had dense eosinophilic cytoplasm (C), but in most instances (D, E) the cytoplasm was pale and flocculent, often with intracytoplasmic inclusions.