"Osteoid osteomas are cortical based benign bone-forming tumours that typically occur in children (particularly adolescents < 30 years of age). They have a characteristic lucent nidus"
"There is growing evidence that osteoid osteoma resolves spontaneously with time and can be treated conservatively with NSAIDs in certain groups of patients 6. The average time to resolution is 33 months 13. Prognosis is considered excellent, with recurrences being uncommon 10."