Retroperitoneal malignant perivascular epithelioid cell tumor: a rare case report and literature review

Background: Perivasuclar epithelioid cell tumor (PEComa) is a rare group of mesenchymal tumors with unique histological and immunophenotypes. Retroperitoneal PEComa is extremely rare and almost benign lesion. Herein, we will present a case from China, focusing on histological and immunohistochemical characteristics of the tumor, follow-up and long-term outcome and the related literature review. Case Description: This 27-year-old Chinese female patient suffered chronical abdominal pain. Transvaginal ultrasound revealed a neoplasm of size 15 cm x 8 cm x 10 cm in the right adnexal region. Following laparoscopy confirmed the mass with multilocular cyst retroperitoneal, adhesion to the right ureter and iliac vessels, and the boundary is unclear, containing about 500 mL turbid fluid. Pathologic immunohistochemical staining indicated HMB-45 (26% positive), SMA (82% positive), Caldesmon (78% positive), Desmin (27% positive), Ki-67 (25% positive), ER (15% positive), PR (12% positive), CDK-4 (5% positive), MiTF WT-1 (negative) and fluorescence in situ hybridization (FISH) test revealed negative with MDM2 gene. A retroperitoneal malignant perivascular epithelioid cell tumor was confirmed finally. The patient was well recovered post the operation. Conclusions: Based on a literature review, there were rare retroperitoneal malignant PEComa reported before, especially the one from China. We wrote this report to arose the attention to this disease, including the diagnosis and antidiastole.