Osteoid Osteoma: Symptoms, Diagnosis, Treatment Osteoid osteoma facts: Osteoid means non-ossifying bone (ground substance of the bone without calcification or ossification) This is a benign tumour, unlike osteosarcoma Lesion is well circumscribed Arises mostly in the cortex of long bones, occasionally in the cancellous bones of the spine. Three times … [Read more...] about Osteoid Osteoma: Symptoms, Diagnosis, Treatment