Perivascular epitheliod cell tumors (PEComas): Presentation of two cases with unusual morphological features

A distinctive group of mesenchymal tumors coexpressing markers of melanocytic and smooth muscle differentiation and presumably derived from perivascular epithelioid cells (PECs) are colligated under the rubric of PEComas. This group of tumors with classical and distinctive histological features is increasingly recognized at various sites. PEComas can occur sporadically or in association with tuberous sclerosis complex. In this report, we present two sporadic cases of PEComa, one sclerosing type arising in an unusual site, the kidney, and the other is an unusual inflammatory variant occurring in the liver. The defining histological features of the sclerosing PEComa in the kidney are bland epithelioid and spindle cells arranged in nests or fascicles surrounded by dense sclerotic stroma with calcifications. In contrast, the inflammatory PEComa in the liver showed a dense inflammatory background with scattered epithelioid cells and adipocytes. Both these tumors were positive for melanocytic markers. These isolated observations will further expand the morphological spectrum of PEComa occurring at unusual sites.