Osteoid osteoma is a benign bone-forming tumour with limited growth potential, inducing disproportionate pain

clinical features :

• pain with nocturnal exacerbation, relieved by salicylates and NSAID
• exquisite, localized tenderness

localization :

• most common in long bones (femur)
• virtually every bone (except sternum)

radiology :

• dense cortical sclerosis around a radiolucent nidus
  • rarely : target-like lesion (if central sclerosis)

histology :

• central nidus :
  • connective tissue, with differentiating osteoblasts producing osteoid and sometimes bone, with or without osteoclasts
• surrounding sclerotic bone