Abstract
Osteoid osteoma is a benign bone tumor that generally presents with nighttime pain among young adults and is relieved by rest and salicylates. It can affect any bone, but occurrences in the iliac are unusual. The authors describe two cases of intramedullary osteoid osteoma next to the sacroiliac joint, with symptoms that simulated sciatic pain. The cases were diagnosed late, although the initial radiographs showed sclerotic lesions in both cases. The diagnosis was confirmed by means of CT scan and the nidus was excised surgically through en bloc resection. The definitive diagnosis was given by means of histopathological examination. Over long-term follow-up, both cases remained asymptomatic and complete bone remodeling at the surgical site was observed. The authors highlight the typical characteristics of the tumor, the unusual location, the differential diagnosis and the treatment.