Osteoid osteoma

 benign osseous tumor usually less than 1.5 cm in diameter, comprising 11% of all benign bone tumors;
           - no cases of malignant transformation has been reported;
    - occurs primarily in adolescents and less often in children;
           - it is rare in patients over age 40 yrs;
    - presenting symptom is well localized pain which may be more severe at night & is relieved by aspirin or other prostaglandin inhibitors;
           - because osteoid osteoma is a vascular tumor, substances which cause vasodilitation such as alcohol may precipitate an acute pain crisis;
    - location:
          - most common site is proximal femur, & diaphysis of long bones;