Aegean Pathology Journal 2, 49–53, 2005 Available on line at www.epd.org.tr/apj.php

Background: Primitive neuroectodermal tumors (PNETs) represent a family of neoplasms, presumed to be of neuroectodermal origin and mostly presenting as bone or soft tissue masses in the trunk or axial skeleton in adolescents and young adults. Case: The patient was 32-year-old man. On gross examination, the tumor measured 16x14 cm in dimensions, with cystic areas and necrosis. Microscopically, the neoplasm was highly cellular consisting sheets of small-round-to-oval cells with irregular nuclei. Immunohistochemical stains were positive for vimentin and CD99. Microscopic and immunohistochemical findings were compatible with PNET. Conclusion: Although rare, PNET must be included in the differential diagnosis of renal tumors especially in children and young adults. We present a case of renal PNET as an unusual case, discuss the differential diagnosis of small round-cell tumors in this location and review the literature