Malignant perivascular epithelioid cell tumor of the kidney with rare pulmonary and ileum metastases.

AIMS To report one case of malignant perivascular epithelioid cell tumor (PEComa) of the kidney with rare pulmonary and ileum metastases and analyze its clinicopathological features. METHODS We analyzed the clinicopathological features of one case of malignant PEComa of the kidney with pulmonary and ileum metastases. Immunohistochemistry staining was performed. RESULTS The patient was a 48-year-old man with a renal mass approximately 14 cm × 11 cm × 8 cm in size. Microscopically, the tumor was mainly composed of polygonal epithelioid cells with dense eosinophilic cytoplasm and round nuclei with small nucleoli. Focal tumor cells showed pleomorphism with multinucleated giant cells and prominent nucleoli. The tumor cells nests were surrounded by thick-walled irregular blood vessels. Focal fat cells were found within the tumor. Hemorrhage and coagulative necrosis were also present. The tumor cells were positive for vimentin, HMB45, and Melan-A, and focally positive for SMA and S-100 protein. After 5 years and 5.6 years of nephrectomy, the tumor metastasized to the right lung and ileum, respectively. CONCLUSION We first reported one case of malignant PEComa of the kidney with pulmonary and ileum metastases. Metastatic PEComa of the lung and ileum should differentiate from primary carcinoma, metastatic carcinoma, malignant melanoma, and gastrointestinal stromal tumor.