Osteoid Osteoma-Ischium

Osteoid osteoma is a benign skeletal neoplasm of unknown etiology that is composed of osteoid and woven bone. Radiography is the initial examination of choice and may be the only examination required. CT is used for precise localization of the nidus and may be used for guiding percutaneous ablation. This is young boy with severe pain especially in night and was relieved by aspirin. Note the lytic lesion with extensive sclerosis surrounding.