Malignant transformation is a rare and late complication of untreated chronic osteomyelitis. Known radiographic findings of the malignant transformation of chronic osteomyelitis are osteolytic or mixed sclerotic and osteolytic lesions with or without soft tissue mass. But its magnetic resonance (MR) imaging findings are rarely described in the literature. We experienced a case of an 82-year-old man diagnosed with squamous cell carcinoma arising from long standing chronic osteomyelitis of the tibia. Our case indicates that radiologists should consider the possibility of malignant transformation in patients with untreated chronic osteomyelitis, with enhancing soft tissue mass invading and extending through underlying bone cortex and medulla on MR imaging.
