To create awareness of the benign lesions from which osteosarcoma may arise.

Osteosarcoma is a rare tumour of bone the etiology of which is poorly understood, but it may arise from benign lesions. Malignant transformation in hemangiomas, in the absence of prior radiation, is exceedingly rare and the resulting neoplasm is usually an angiosarcoma. We report the case of a 30-year-old woman where investigation for thigh pain revealed a distal femoral hemangioma. She represented with pain and mass 18 years later, leading to a confirmed diagnosis of osteosarcoma at the same site.

Osteosarcomas may arise from a variety of benign lesions. In this article we report the case of a histologically confirmed hemangioma which subsequently underwent malignant change into an osteosarcoma.