A rare presentation of osteoid osteoma in a rib and unexpected

Osteoid osteoma (OO) is a relatively common skeletal neoplasm, frequently involves long bones. OO of rib is extremely rare, including 0.23-2% of OO cases. Most of them arose in posterior arc, frequently in its head or neck and might lead to painful scoliosis. Involvement of anterior aspect of a rib is extremely rare. Skeletal scintigraphy is highly sensitive for detection of OO. “Double density sign"; a typical pattern in bone scintigraphy is usually seen in OO of cortical bones. The current study presents a case of 22-year-old man with OO in anterior arc of a rib, revealed double density sign on 99mTc-MDP scan.