To date, 13 cases of sporadic renal hemangioblastoma have been reported. In this article, we report such a case that might cause the diagnostic pitfall. A 37-year-old Japanese was found to have a renal mass by periodic medical check-up. He underwent radical nephrectomy. Macroscopically, the tumor was well-defined without fibrous capsule and the cut surface of the tumor exhibited light brown to gray-tan color without hemorrhage or necrosis. Microscopically, the tumor was made up of large polygonal to short spindle cells with eosinophilic cytoplasm with occasional vacuolization and abundant arborizing capillary network. Immunohistochemically, neoplastic cells showed diffuse positivity for inhibin-alpha, S-100 protein, vimentin, CA9, PAX2 and PAX8, but negativity for cytokeratin CAM5.2, alpha smooth muscle actin, Melanosome, Melan A, TFE3 and cathepsin K. In genetic analyses, this tumor showed no changes of VHL gene mutation, hypermethylation and loss of heterozygosity of chromosome 3p. Additionally, G-band karyotype and array comparative genomic hybridization studies showed a normal chromosome. In conclusion, the positivity for CA9, PAX2 and PAX8 in sporadic renal hemangioblastoma may cause the critical diagnostic pitfall in the differential diagnosis from clear cell renal cell carcinoma. Pathologists need to pay attention to systemic evaluation including macroscopic, microscopic and immunohistochemical findings. In some cases, molecular genetic study may be necessary.

• Keywords
• CA9, Hemangioblastoma, PAX2, PAX8, kidney,
• MeSH
• Antigens, Neoplasm metabolism   MeSH
• Diagnosis, Differential MeSH
• Adult MeSH
• Hemangioblastoma diagnosis   metabolism   pathology   MeSH
• Carbonic Anhydrase IX MeSH
• Carbonic Anhydrases metabolism   MeSH
• Carcinoma, Renal Cell diagnosis   metabolism   pathology   MeSH
• Humans MeSH
• Biomarkers, Tumor metabolism   MeSH
• Kidney Neoplasms diagnosis   metabolism   pathology   MeSH
• PAX2 Transcription Factor metabolism   MeSH
• PAX8 Transcription Factor MeSH
• Paired Box Transcription Factors metabolism   MeSH
• Check Tag
• Adult MeSH
• Humans MeSH
• Male MeSH
• Publication type
• Journal Article MeSH
• Case Reports MeSH
• Names of Substances
• Antigens, Neoplasm MeSH
• CA9 protein, human MeSH Browser
• Carbonic Anhydrase IX MeSH
• Carbonic Anhydrases MeSH
• Biomarkers, Tumor MeSH
• PAX2 protein, human MeSH Browser
• PAX8 protein, human MeSH Browser
• PAX2 Transcription Factor MeSH
• PAX8 Transcription Factor MeSH
• Paired Box Transcription Factors MeSH

We present a series of a distinct tumorous entity named renal angiomyoadenomatous tumor (RAT). Five cases were retrieved from the consultation files of the authors. Histologic and immunohistochemical features were evaluated. Sequencing analysis of coding region of the VHL gene was carried out in all cases. The tumors were composed of admixture of an epithelial clear cell component and prominent leiomyomatous stroma. Epithelial cells formed adenomatous tubular formations endowed with blister-like apical snouts. All tubular/glandular structures were lined by a fine capillary network. The epithelial component was positive for epithelial membrane antigen, CK7, CK20, AE1-AE3, CAM5.2, and vimentin in all cases. In all analyzed samples, no mutation of the VHL gene was found. RAT is a distinct morphologic entity, being different morphologically, immunohistochemically, and genetically from all renal tumors including conventional clear cell carcinoma and mixed epithelial and stromal tumor of kidney.

• MeSH
• Adenoma genetics   metabolism   pathology   MeSH
• Biomarkers metabolism   MeSH
• Epithelial Cells pathology   MeSH
• Keratin-20 metabolism   MeSH
• Keratin-7 metabolism   MeSH
• Keratins metabolism   MeSH
• Middle Aged MeSH
• Humans MeSH
• Mucin-1 metabolism   MeSH
• Mutation MeSH
• Von Hippel-Lindau Tumor Suppressor Protein genetics   MeSH
• Kidney Neoplasms genetics   metabolism   pathology   MeSH
• Aged, 80 and over MeSH
• Aged MeSH
• Vimentin metabolism   MeSH
• Loss of Heterozygosity MeSH
• Check Tag
• Middle Aged MeSH
• Humans MeSH
• Male MeSH
• Aged, 80 and over MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Case Reports MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Biomarkers MeSH
• CAM 5.2 antigen MeSH Browser
• Keratin-20 MeSH
• Keratin-7 MeSH
• Keratins MeSH
• Mucin-1 MeSH
• Von Hippel-Lindau Tumor Suppressor Protein MeSH
• VHL protein, human MeSH Browser
• Vimentin MeSH