The findings on x-ray and MRI are typical for osteochondroma, a common benign bone tumor, often asymptomatic, solitary, and with a low rate of malignant transformation. When multiple and symmetrical, these lesions may be associated with hereditary multiple exostoses syndrome. Typical lesions are usually found in long bones, at the metaphyseal region, and can be pedunculated, sessile, or cauliflower-shaped, with ring-and-arc calcifications, a cartilage cap, and continuity between the cortex and medullary cavity of the lesion with the healthy bone. These can occur at any age, with no malignant features such as periosteal reaction, soft tissue mass formation, or cortical destruction.

Some features of malignant transformation that should be noted are as follows:

• G: growth after skeletal maturity

• L: lucency (new)

• A: additional scintigraphic activity

• D: destruction (cortical)

• P: pain after puberty

• a: and

• S: soft tissue mass

• T: thickened cartilage cap >1.5 cm