<prompt> Aspirin is useful in which type of bone tumor:OsteonecrosisOsteopetrosisOsteoid osteomaEwing sarcoma  <response>: Ans. c Osteoid osteomaRef: Maheshwari 5th ed. 235 Osteoid osteoma is a benign bone tumour characterized by pain which is relieved by non-steroidal anti- inflammatory drugs NSAIDs, such as aspirin. To clarify the mechanism of the pain, five osteoid osteomas were studied immune-histochemically using polyclonal antibodies against prostaglandin E2 PGE2, S-100 protein and protein gene product. 