<unk> -cell<unk>  of the<unk>  (GCTOB), is a relatively uncommon<unk>  of the<unk> . It is characterized by the presence of multinucleated<unk> <unk> s (osteoclast-like<unk> s). Malignancy in<unk> -cell<unk>  is uncommon and occurs in about 2% of all cases. However, if malignant degeneration does occur, it is likely to metastasize to the lungs.<unk> -cell<unk> s are normally benign, with unpredictable behavior. It is a heterogeneous<unk>  composed of three different<unk>  populations. The<unk> -cell<unk> r stromal<unk> s (GCTSC) constitute the neoplastic<unk> s, which are from an osteoblastic origin and are classified based on expression of osteoblast<unk>  markers such as alkaline phosphatase and osteocalcin. In contrast, the mononuclear histiocytic<unk> s (MNHC) and multinucleated<unk> <unk>  (MNGC) fractions are secondarily recruited and comprise the non-neoplastic<unk>  population. They are derived from an osteoclast-monocyte lineage determined primarily by expression of CD68, a marker for monocytic precursor<unk> s. In most patients, the<unk> s are slow to develop, but may recur locally in as many as 50% of cases.
Giant-cell tumor of bone
Osteomyelitis
Fibrocartilaginous mesenchymoma of bone
Osteoid osteoma
Osteoblastoma
Osteoma cutis
Fibrous dysplasia of bone
Bone cyst