Giant cell tumor of bone. A cytologic study of 24 cases.

Twenty-three patients with radiologic diagnoses of giant cell tumor of bone underwent fine needle aspiration cytology and needle biopsy for tissue diagnosis before curettage or resection. One patient had two tumors, making a total of 24 cases. The accuracy of the cytologic diagnosis was compared with that of tissue biopsy. Cytologically there were mononucleated and multinucleated cells. The former often occurred in clusters or, less often, were dispersed. They had spindle or plump cell bodies with moderate amounts of cytoplasm and well-defined cytoplasmic membranes. The oval nuclei demonstrated fine, evenly distributed chromatin and small nucleoli. The multinucleated cells were osteoclastlike and were associated with the clusters of mononucleated cells or lying freely. They had a well-demarcated cytoplasm and contained from a few to several dozen monomorphic nuclei. Cytologic diagnosis was made in 20 of 24 cases, and histologic diagnosis was made in 21 of 24. Insufficient diagnostic material for cytology was the reason for failure in 4 cases. This was attributed to faulty technique (2 cases), cystic change (1 case), and massive necrosis (1 case). As other benign and malignant bone tumors may contain benign giant cells, cytologic or histologic findings alone are not diagnostic of giant cell tumor of bone, but should be complemented with the clinicoradiologic findings. Aspiration cytology is as accurate as tissue needle biopsy, may be of high diagnostic value in deeply located lesions not amenable to cutting needle biopsy, and should be done with full knowledge of the clinicoradiographic information.