Primary renal sclerosing epithelioid fibrosarcoma: A case report.

Sclerosing epithelioid fibrosarcoma (SEF) is a rare variant of fibrosarcoma that primarily arises in the deep soft tissue of the extremities and trunk. Primary SEF in the visceral organs is rare, and only a few cases have been reported. A 20-year-old man was diagnosed with primary renal SEF metastatic to the lymph nodes and bone, which was managed with open right radical nephrectomy and ongoing chemotherapy. Immunohistochemical staining for MUC-4, vimentin, BCL-2, and EMA was positive in tumor cells. Next-generation sequencing revealed the presence of EWSR-CREB3L1 gene fusions and SMARCB1 rearrangement in exon 6.