osteoidoma

Osteoid osteoma is a benign bone-forming tumor that typically affects young adults, commonly found in the long bones of the lower extremities, such as the femur and tibia. It can also occur in the spine and other bones. The hallmark symptom is pain, which is often described as a deep, gnawing ache that is characteristically worse at night and relieved by nonsteroidal anti-inflammatory drugs (NSAIDs) like aspirin or ibuprofen. This nocturnal pain is attributed to the release of prostaglandins from the tumor.

Radiographically, osteoid osteoma is characterized by a small nidus, which is a central area of abnormal bone formation, surrounded by a zone of reactive sclerosis, or hardening of the bone. The nidus is typically less than 1.5 centimeters in diameter. Diagnosis is usually made through a combination of clinical presentation, imaging studies such as X-rays, CT scans, and sometimes MRI. CT scans are particularly useful for precisely identifying the nidus.

The exact cause of osteoid osteoma is unknown, but it is thought to be a reactive lesion rather than a true neoplastic process. Histologically, it shows a central core of osteoid and woven bone, surrounded by a rim of sclerotic bone and fibrous tissue. While osteoid osteoma is benign and does not metastasize, it can cause significant pain and functional impairment if left untreated. Treatment options include conservative management with NSAIDs for symptom control, percutaneous radiofrequency ablation of the nidus, and in some cases, surgical resection. Percutaneous ablation has become the preferred treatment for many symptomatic osteoid osteomas due to its high success rate and minimally invasive nature.