Virus-like intranuclear inclusions in giant cell tumor of bone.

An ultrastructural study of 13 cases of typical giant cell tumor of bone (GCT) revealed the presence of virus-like intranuclear inclusions (INI), morphologically identical to those reported in Paget's disease of bone. In two giant cells of two different patients, INI were found only after careful survey of a great number of cells. This finding, coupled with the scarcity of GCT with similar inclusions reported in the literature, reveals the extreme rarity of this finding and leaves open to discussion the specificity of these INI even in Paget's disease, as well as the possible etiological significance in giant cell tumor of bone.