Melanotic epithelioid clear cell tumor of kidney: report of three cases / 中华病理学杂志

ABSTRACT

<p><b>OBJECTIVE</b>To study the pathologic features and immunophenotype of 3 cases of melanotic epithelioid clear cell tumor of kidney.</p><p><b>METHODS</b>More than 2000 cases of renal tumors were retrospectively reviewed. Three cases of melanotic epithelioid clear cell tumor were identified. Immunohistochemical study was carried out using the paraffin-embedded tissue samples. Electron microscopy was also performed in 1 case.</p><p><b>RESULTS</b>Amongst the 3 cases studied, the male-to-female ratio is 1:2. Histologically, 2 cases showed a clear cell carcinoma-like pattern. Papillary structures covered by clear cells and eosinophilic cells were observed in 1 case. Immunohistochemical study showed that the tumor cells in all cases expressed HMB 45. Two of them were also positive for Melan A. The staining for epithelial markers and S-100 protein was negative. Melanosomes were not identified by ultrastructural examination.</p><p><b>CONCLUSIONS</b>Melanotic epithelioid clear cell tumor is a rarely seen neoplasm of kidney. There are some histologic overlaps with renal cell carcinoma, epithelioid angiomyolipoma and melanoma. Immunohistochemical study is useful in confirming the diagnosis. The tumor represents a morphologic variant of epithelioid angiomyolipoma.</p>