LAUSR

INTRODUCTION Perivascular epithelioid cell (PEC) is a cell type constantly present in a group of tumours including angiomyolipoma (AML), clear-cell «sugar» tumour (CCST) of the lung and extrapulmonary sites, lymphangioleiomyomatosis (LAM), and clear-cell tumours of other anatomical sites. It has morphologic distinctive features: epithelioid appearance with a clear to granular cytoplasm, a round to oval, centrally located nucleus and an inconspicuous nucleolus. Immunohistochemically, PEC expresses myogenic and melanocytic markers. Eleven cases of primary bone PEComa presentation have been described since 2002. OBJECTIVE To report a case of primary bone perivascular epithelioid cell tumour. CASE REPORT 24 year-old male presented with pain. X-ray revealed an osteolytic lesion at right proximal tibia with soft tissue extension. Evaluation of slides identified a bony perivascular epithelioid cell tumour without immunohistochemical study confirmation. RESULTS Patient was treated by surgical excision and adjuvant chemotherapy (epirubicin/cysplatin). After two years of follow-up the patient remains disease free. CONCLUSIONS This is the first-case report in Latin America. Immunohistochemical stains were negative and we believe it may be due to non-described ethnic variations.