Ostéosarcome extrasquelettique d’emblée métastatique révélé par une masse occipitale

Abstract

Extraskeletal osteosarcoma is a rare mesenchymatous tumour occurring in adults aged over 50 years and is located mainly in the limbs or retroperitoneum. We report a case of metastatic extraskeletal osteosarcoma revealed by a cutaneous occipital tumour site. A 53-year-old woman was admitted for dyspnea and weight loss. An occipital tumour, noticed for one year by the patient, was discovered. It was freely movable on the bone, of hard consistency and responsible for alopecia. In addition to left-sided pleural effusion, a chest CAT revealed a large mass in the left lung, including areas of necrosis and calcifications with intracardiac extension. Histological examination of biopsies of the skin and of pulmonary and intracardiac lumps showed an osteosarcomatous proliferation. No primary osteosarcoma was found in the bones. A diagnosis was made of metastatic extraskeletal osteosarcoma. Intravenous chemotherapy was given followed by radiotherapy. After a six-month stabilization period, the disease progressed. Extraskeletal cutaneous locations of osteosarcoma are extremely rare. They may comprise either the primary tumour or a metastatic lesion. In this patient, the immediately metastatic nature of the disease was a poor prognostic factor for this high-grade sarcoma.