Tibial perivascular epithelioid cell tumour (PEComa). A case report and literature review. / Neoplasia de células epiteloides perivasculares (PEComa) tibial. Reporte de un caso y revisión de la literatura.

INTRODUCTION: Perivascular epithelioid cell (PEC) is a cell type constantly present in a group of tumours including angiomyolipoma (AML), clear-cell «sugar¼ 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.

[Bone liposclerosing myxofibrous tumor. Case presentation and literature review]. / Tumor fibromixoma lipoesclerosante óseo. Presentación de un caso y revisión de la literature.

The bone liposclerosing myxofibrous tumor (LSMFT) was initially described by Ragsdale in 1986 as a polymorphic fibroosseous bone lesion with a mix of histologic elements that include lipoma, fibroxanthoma, myxoma, myxofibroma, fat necrosis, ischemic ossification, areas of fibrous dysplasia, and infrequent presence of cartilage or cystic changes. The most frequently reported location is the intertrochanteric area of the femur. Radiologically it is a lytic, geographic lesion, with well-defined margins and usually sclerotic. In some cases findings include mineralization inside the lesion or a certain degree of expansion to the contour. The close relationship between LSMFT and fibrous dysplasia has been described based on the histologic characteristics and the presence of the Gsα mutation. Another hypothesis of the etiology of the lesion is the reaction of fibrous dysplasia to stress.