Comparison of cytologic features of giant-cell tumor and giant-cell tumor of tendon sheath.

The cytologic features in twelve cases of giant-cell tumor (GCT) and five cases of giant-cell tumor of tendon sheath (GCTTS) diagnosed by fine-needle aspiration cytology (FNAC) are described. All of these cases were histopathologically confirmed. The aspirates of GCT are composed of a dual population of mononucleated spindle cell and multinucleated giant cells. The peripheral adherence of giant cells to the spindle cell is the feature of diagnostic significance in GCT. In GCTTS, the aspirate consists of a polymorphic population composed of mononuclear histiocyte-like cells, hemosiderin laden macrophages, foamy macrophages, and a few multinucleated giant cells. FNAC can be used as a diagnostic tool for an early and accurate detection of these two giant cell-rich lesions, since the cytologic features when evaluated in conjunction with the clinical and radiologic features are sufficiently diagnostic.