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.

Background: Hemangioblastoma is a benign tumor of unknown histogenesis that mainly occurs in the central nervous system (CNS) associated with von Hippel-Lindau (VHL) disease. Much attention has been paid to the renal hemangioblastoma, but there are still some challenges in the differential diagnosis.Case presentation: Here, we describe three cases of sporadic renal hemangioblastoma with no clinical features of VHL diseases. All the three patients (male: 2; female: 1) were 40-56 years old. In all cases, the tumors were surrounded by a thick fibrous capsule and well-demarcated from the surrounding renal parenchyma. Tumors were composed of sheets or nests of polygonal to short spindle tumor cells and a rich capillary network. In case 1 and case 3, the large polygonal tumor cells contained abundant pale or eosinophilic cytoplasm, and some of the cells possessed intracytoplasmic lipid vacuoles. In case 2, tumor cells were characterized by uniform size, mild, clear or lightly stained cytoplasm and typical "clear cell" appearance. In the views of immunohistochemistry, the polygonal stromal cells were strongly and diffusely positive for α-inhibin, NSE, S100 protein, and vimentin. CD10 and PAX8 were positive, while EMA and CK showed focally positive in case 3. CK8/18, HMB45, MelanA, CgA, Syn, SMA, Desmin and CD56 were all negative. CD34 and CD31 outlined the contours and distribution of vascular networks in tumors. Conclusions: Renal hemangioblastoma is rare and prone to be misdiagnosed. More attention should be paid to the morphological features and reasonable application of immunohistochemistry for the diagnosis of hemangioblastoma.