Sporadic hemangioblastoma of the kidney: a clinicopathologic study of three cases and a literature review.

Much attention has been paid to renal hemangioblastoma, but there are still challenges in its differential diagnosis. Three cases (2 men, 1 woman; age: 40-56 years) presented with renal tumors. The tumors were surrounded by a thick fibrous capsule, well-demarcated from the surrounding renal parenchyma, and composed of sheets or nests of polygonal to short spindle-shaped tumor cells with a rich capillary network. In cases 1 and 3, the large polygonal tumor cells contained abundant pale or eosinophilic cytoplasm, and some possessed intracytoplasmic lipid vacuoles. In case 2, tumor cells were characterized by a uniform size, mild, clear, or lightly stained cytoplasm, and typical "clear cell" appearance. Immunohistochemistry revealed that the polygonal stromal cells were strongly and diffusely positive for α-inhibin, neuron-specific enolase (NSE), S100 protein, and vimentin. Cluster of differentiation (CD)10 and paired box gene (PAX)8 were positive, while epithelial membrane antigen (EMA) and cytokeratin (CK) were focally positive in case 3. CD34 and CD31 outlined the contours and distribution of the vascular networks. Renal hemangioblastoma is rare and prone to misdiagnosis; more attention should be paid to the morphological features and reasonable application of immunohistochemistry in the diagnosis of hemangioblastoma.