Primary sclerosing epitheloid fibrosarcoma of the kidney: First case reported in Mexico.

Here we reported a case of primary sclerosing epitheloid fibrosarcoma (SEF) of the kidney, an extremely rare and aggressive tumor. The patient presented a mass in the upper part of the right kidney with pulmonary metastasis at the time of diagnosis, a right radical nephrectomy was performed, it was a solid tumor of 15 cm × 9 cm affecting almost the entire kidney. Histological study revealed a neoplasm of uniform epithelioid cells with scant cytoplasm with dense and sclerotic stroma. immunohistochemistry positive for MUC-4, detection by fusion of EWSR1-CREB3L1 by FISH positive.