<unk>  is the third most common benign bone tumor. Its incidence is 11% among the benign tumors and 3% among all primary bone tumors. Adolescents and children are most affected by<unk> . Men are more commonly affected than women, with a 6:4 ratio.<unk>  is a benign osteoblastic tumor that was first described in 1930 by Bergstrand. Jaffe described it in 1935 and was the first to recognize it as a unique entity.<unk> s are usually smaller than 1.5-2 cm and characterized by an<unk> -rich nidus in a highly loose, vascular connective tissue. The nidus is well demarcated and may contain a variable amount of calcification. Surrounding the nidus is a zone of sclerotic but otherwise normal bone.<unk>  can occur anywhere.<unk>  is usually occur in the cortex of the shafts of long bones more than 50% of the cases. It is seen in the metaphyseal regions of large bones of the femur, tibia, and humerus. About 20% percent of the lesions involve posterior element of the spine. The hallmark of<unk>  is intense nocturnal limb pain which is relieved by low doses of salicylates and local tenderness. If left untreated,<unk>  progression occurs slow and is then followed by restricted range of motion, possible pathologic fracture, or spontaneous regression. The medical therapy for<unk>  is NSAIDs and the mainstay of treatment is surgery.
Osteoid osteoma
Osteochondroma
Osteoma
Aneurysmal bone cyst
Osteochondrosis
Osteoblastoma
Unicameral bone cyst
Giant cell tumor of bone