A clinicopathological study of giant cell tumor of small bones

BACKGROUND AND PURPOSE: Giant cell tumor (GCT) of the small bones (small-bone GCT) is usually rare and considered somewhat different from conventional GCT. The purpose of this study was to investigate and report the clinicopathological features of 11 cases with small-bone GCT. MATERIALS AND METHODS: Patient information was obtained with the help of questionnaires. X-rays and paraffin blocks obtained from several institutions were clinically, radiographically, and histologically evaluated. RESULTS: Small-bone GCT was observed in younger patients compared to conventional GCT; 5 of the 11 (45%) patients were below 20 years of age, whereas the corresponding figure for all GCT patients is 16% in Japan. Excessive cortical bone expansion is a special feature. There were two cases of recurrence and one case of lung metastasis; the primary lesion was in the hand for all three cases. In contrast, no primary lesion of the foot recurred or metastasized. Varying degrees of positive p63 immunostaining were observed in all examined cases (n = 9) of small-bone GCT but were negative in case of giant cell reparative granuloma (GCRG) and solid variant of aneurysmal bone cyst (ABC). One case that demonstrated high-intensity positive staining had two episodes of recurrence. CONCLUSION: Small-bone GCT tends to develop in younger patients than does conventional GCT. Primary GCTs of the hand may be biologically more aggressive than those of the feet. The p63 immunostaining may be useful not only for differential diagnosis but also for prognostication of small-bone GCT.