RESUMO
<p><b>OBJECTIVE</b>To study the clinicopathologic characteristics of primary renal hemangioblastoma.</p><p><b>METHODS</b>The morphologic features, immunophenotype and molecular findings of 3 cases of primary renal hemangioblastoma were studied, with review of literature.</p><p><b>RESULTS</b>The age of patients ranged from 43 to 57 years. There were 2 women and a man. The patients often presented with renal mass. Histologically, the tumors were surrounded by thick fibrous capsule and composed of epithelioid or spindle cells. Two cases had a prominent stromal component and the other one was rich in capillary network. Lipid vacuoles were observed in all cases. Features of hemorrhage were demonstrated in 2 cases. Capsular invasion and necrosis were seen in 1 case. Immunohistochemical study showed that the stromal cells were positive for alpha-inhibin (3/3), S-100 protein (3/3), EGFR (2/2), PAX-2 (2/2), PAX-8 (2/2) and CA9 (2/2) but negative for CKpan (2/2) and HMB45 (2/2). Focal membranous staining for CD10 (3/3) was noted. No VHL gene mutations or chromosome 3p deletion were detected in the 2 cases studied.</p><p><b>CONCLUSIONS</b>Renal hemangioblastoma shows distinctive morphologic appearance with a wide range of variation. The unexpected positive staining for PAX-2, PAX-8 and CD10 in renal hemangioblastoma needs to be aware. Immunohistochemical study may be helpful in differential diagnosis of these renal tumors.</p>
RESUMO
<p><b>OBJECTIVE</b>To study the clinicopathologic features, immunophenotype, differential diagnosis and prognosis of renal cell carcinoma (RCC) associated with t(6;11)(p21.2;q13)/MALAT1-TFEB gene fusion.</p><p><b>METHODS</b>A total of 9 cases of such rare tumor were selected for clinicopathologic, immunohistochemical and molecular analysis, with review of literature.</p><p><b>RESULTS</b>The age of the patients ranged from 21 to 42 years (mean=31.3 years). The patients included four men and five women. Histologically, 4 of the 9 cases studied showed classic morphologic features of TFEB RCC, with hyaline material, pigments and psammoma bodies frequently identified. The remaining 5 cases demonstrated uncommon morphology, mimicking perivascular epithelioid cell neoplasm, clear cell RCC, chromophobe RCC or papillary RCC. Immunohistochemical study showed that TFEB and vimentin were positive in all cases. Most of the tumors studied also expressed Ksp-cadherin, E-cadherin, CD117, HMB45, Melan A and Cathepsin K. CKpan showed immunostaining in only 1 case. The staining for TFE3, CD10 and CK7 were all negative. TFEB gene rearrangement was detected in all the 9 cases studied using fluorescence in-situ hybridization. MALAT1-TFEB fusion gene was identified in 2 cases by polymerase chain reaction and direct sequencing. TFEB RCC seemed to be an indolent tumor. During a mean follow-up of 31 months, none developed tumor recurrence, progression, or metastasis.</p><p><b>CONCLUSIONS</b>TFEB fusion-associated RCC is a rare neoplasm, tends to occur in young age group and carries an indolent behavior. Diagnosis relies on clinicopathologic findings and immunohistochemical analysis. TFEB break-apart FISH assay is a reliable tool in confirming the diagnosis.</p>