Pseudomalignant myositis ossificans mimicking osteosarcoma: a case report.

An ossifying soft-tissue lesion is potentially malignant. The possibility of malignancy increases in the absence of significant trauma. Pseudomalignant myositis ossificans can be easily confused with malignant lesions. A 22-year-old man presented with an ossifying mass in the adductor compartment of the thigh. The mass was excised and histopathologically reported as a soft-tissue osteosarcoma, but was later confirmed as pseudomalignant myositis ossificans by a pathologist specialising in oncology. Careful consideration and correlation of clinical, radiological, and histopathological findings is required to ensure the correct diagnosis is made and both initial and ongoing management is appropriate.