<unk>  is a relatively uncommon<unk>  of the bone. It is characterized by the presence of multinucleated<unk> <unk> s (osteoclast-like<unk> s).<unk>  accounts for 4-5% of primary bone<unk> s and 18.2% of benign bone<unk> s.<unk>  almost invariably occur when the growth plate has closed and are therefore typically observed in early adulthood, with 80% of cases reported between the ages of 20 and 50, with a peak incidence between 20 and 30.<unk>  typically occur as single lesions. They usually prefers the epiphyses of long bones. Although any bone can be affected, the most common sites are distal femur, proximal tibia, and distal radius. The progression to<unk>  usually involves the over-expression in RANK/RANKL signalling pathway with resultant over-proliferation of osteoclasts. On gross pathology, hemorrhage, presence of co-existent aneurysmal bone cyst, and fibrosis are characteristic findings of<unk> . On microscopic histopathological analysis, prominent and diffuse osteoclastic<unk> <unk> s and mononuclear<unk> s with frequent mitotic figures are characteristic findings of<unk> . Symptoms of<unk>  include localized pain, localized swelling, and decreased range of motion. Physical examination findings will depend on the location of the<unk> <unk><unk> . Common physical examination findings of<unk> <unk><unk>  are localized swelling and tenderness at the site of the<unk> .<unk>  must be differentiated from aneurysmal bone cyst, chondroblastoma, simple bone cyst, osteoblastoma,giant<unk>  rich osteosarcoma, and brown<unk>  of hyperparathyroidism. X-ray may be helpful in the diagnosis of<unk> . Common complications of<unk> <unk><unk>  include malignant transformation, recurrence, and metastasis. Findings on x-ray suggestive of<unk> <unk><unk>  include metaepiphyseal location of mass and grow to the articular surface of the involved bone with narrow zone of transition. Surgery is the mainstay of treatment for<unk> <unk><unk> .
Giant cell tumor of bone
Osteoid osteoma
Osteoblastoma
Primary lymphoma of the bone
Aneurysmal bone cyst
Osteoma
Paget's disease of bone
Diffuse idiopathic skeletal hyperostosis