Clinical and radiological features of atypical giant cell tumours of bone

Abstract

Giant cell tumour (GCT) of bone is an uncommon neoplasm, representing approximately 5% of all bone neoplasms and approximately 21% of benign bone tumours (Dahlin & Unni, 1986). The vast majority of GCTs arise after closure of the growth plate and occur at the end of long bones. GCTs are frequently diagnosed by radiologists because of their preferred location (80% in long bones of the extremities), age distribution (peak incidence in the third decade) and morphologic appearance. Typically, they are expanding radiolucent lesions eccentrically located, most commonly at the articular surface of a long bone. Pathologic and histologic findings are characteristic, although these tumours need to be differentiated from other lesions containing giant cells, such as non-ossifying fibroma, aneurysmal bone cyst, osteoblastoma, chondroblastoma, giant cell reparative granuloma, benign fibrous histiocytoma and brown tumours. The biologic behaviour of GCT frequently is not predictable. In our experience, shared by most authors, histologic grading as a guide to prognosis is of no practical value (Schajowicz, 1981). On the contrary, radiologic features (“quiescent”, “active”, “aggressive”) are a more reliable indication of local clinical behaviour (Campanacci et al, 1987). GCTs are often aggressive in behaviour with a distinct tendency toward local recurrence, most often within the first post-operative years (McDonald et al, 1986). We present a collection of unusual GCTs (excluding those of the facial bones) from 465 histologically proven cases from the Latin American Tumor Registry and St Louis University.