Sclerosing Perivascular epithelioid cell neoplasms (PEComa), a rare variant in a unique family of tumors

Abstract Introduction/Objective Perivascular epithelioid cell neoplasms (PEComas) are a rare group of neoplasms that characteristically show both smooth muscle and melanocytic differentiation. The most common tumor in this family is renal angiomyolipoma but may occur in various sites. Sclerosing PEComa (S-PEComa) is an extremely rare variant. its only reported in females and it is usually an incidental finding in the retroperitoneum, in close proximity to the kidney. Methods/Case Report . We present a 52-year-old female, who had a chest CT scan for worsening cough. An - 4 cm exophytic renal mass in the left renal upper pole was found. Patient underwent left partial nephrectomy. Grossly the specimen consisted of 2.5 cm well-circumscribed, white tan mass, abutting the renal capsule, and extending into perinephric adipose tissue. Histology revealed uniform bland epithelioid cells with palely eosinophilic cytoplasm and round nuclei embedded in abundant densely sclerotic stroma. No fat was identified. Immunohistochemistry showed the tumor to be positive for desmin, HMB-45 and SMA with focal staining for AE1/AE3 and negative staining for EMA, cam 5.2, CD 117, calretinin, CD 34, S-100, PAX 8, and Melan A, which confirming the diagnosis of S-PEComa. Results (if a Case Study enter NA) NA Conclusion PEComas, excluding the epithelioid variant, usually has a benign course. In the 13 cases previously reported S-PEComa, 2 patients had metastasis. Our patient, 3-month post-op, has no evidence of disease, but close follow up still warranted.