High magnification micrograph of<unk> <unk> s in a<unk> , H&E stain The diagnosis of<unk> -cell<unk> s is based on biopsy findings. The key histomorphologic feature is, as the name of the entity suggests, (multinucleated)<unk> <unk> s with up to a hundred nuclei that have prominent nucleoli. Surrounding mononuclear and small multinucleated<unk> s have nuclei similar to those in the<unk> <unk> s; this distinguishes the lesion from other osteogenic lesions which commonly have (benign) osteoclast-type<unk> <unk> s. Soap-bubble appearance is a characteristic feature. Imaging X-ray of a<unk> -cell bone<unk>  in the head of the fourth metacarpal of the left hand On X-ray,<unk> -cell<unk> s (GCTs) are lytic/lucent lesions that have an epiphyseal location and grow to the articular surface of the involved bone. Radiologically the<unk> s may show characteristic 'soap bubble' appearance. They are distinguishable from other bony<unk> s in that GCTs usually have a nonsclerotic and sharply defined border. About 5% of<unk> -cell<unk> s metastasize, usually to a lung, which may be benign metastasis, Plain radiograph is still the main method of diagnosing<unk> <unk> <unk> r. But MRI and CT scans are useful for staging and surgical planning. CT is more superior than plain radiograph in delineating the<unk> r outline, its extension into structures outside the bone, determining the involvement of bony cortex and<unk> r recurrence. CT scans show features such as thin and expanded bony cortex, with or without bony matrix calcifications, and fluid levels due to aneurysmal bone cyst or bleeding within<unk> r. However, axial views of the subarticular bone (bony area adjacent to the articular cartilage) is not accurate due to voxel signal averaging. MRI is superior than CT on delineating the<unk> r because of its better contrast resolution and imaging in multiple planes. MRI is also useful in determining the extension outside the bone and evaluating the involvement articular surface, skip lesions within bony matrix, and medullary cavity. However, bony cortex destruction is better demonstrated on CT scan. On MRI, the mass produces intermediate to reduced signal intensity on T1-weighted images, and increased signal intensity on fluid sensitive MRI images such as short tau inverstion recovery (STIR). The mass enhances after intravenous gadolinium administration. Differential diagnosis A number of<unk> s have<unk> <unk> s, but are not true benign<unk> -cell<unk> s. These include, aneurysmal bone cyst, chondroblastoma, simple bone cyst, osteoid osteoma, osteoblastoma, osteosarcoma,<unk> -cell reparative granuloma,<unk> -cell<unk>  of the tendon sheath and brown<unk>  of hyperparathyroidism.
Giant-cell tumor of bone
Osteomyelitis
Fibrocartilaginous mesenchymoma of bone
Osteoid osteoma
Osteoblastoma
Osteoma cutis
Fibrous dysplasia of bone
Bone cyst