[Primary cutaneous osteosarcoma].

BACKGROUND: Osteosarcoma is a malignant tumor of mesenchymatous origin that chiefly affects the metaphysis of long bones. The extraskeletal form of the disease is rare, and even rarer is a cutaneous site, whether metastatic or primary. Herein, we report a new case of primary cutaneous osteosarcoma. PATIENTS AND METHODS: A 54-year-old woman presented a hard subcutaneous nodular tumor on her left arm noted 1 year earlier. The diagnosis of cutaneous osteosarcoma was made on the basis of histological analysis of the lesion, which showed a sarcomatous dermal-hypodermal proliferation secreting osteoid. Clinical and radiological staging ruled out any extra-cutaneous spread, particularly to bone, thus confirming the primary cutaneous nature of the osteosarcoma. DISCUSSION: Primary cutaneous osteosarcoma is a rare tumor, diagnosis of which is normally based on histopathological features.