Giant-cell tumours and aneurysmal bone cysts of the spine. With special reference to the problems related to the removal of a vertebral body.

Giant-cell tumours of bone were probably first described by Cooper and Travers in 1818. N#{233}laton (1860) designated them “ tumeurs a myeloplaxes.” The name giant-cell tumour was introduced by Bloodgood (1919). Stewart (1922) regarded the giant cells as an integral part Of the growth and believed that they were related to the osteoclasts of normal bone; he proposed the term osteoclast sarcoma, from which the name osteoclastoma developed. In many older publications the diagnosis of giant-cell tumour of bone has been applied with insufficient precision, to include various other bone lesions in which multinucleated giant cells were found. In 1940 Jaffe, Lichtenstein and Portis attempted to define what should properly be regarded as a genuine giant-cell tumour. In their opinion it is a distinctive neoplasm arising from the non-osteogenic supporting connective tissue of the marrow, which can be readily identified on the basis of its cytological details. Special tumour types previously classified as giant-cell tumours were recognised as separate entities, such as benign chondroblastoma of bone, non-osteogenic fibroma of bone and aneurysmal bone cyst. Jaffe and Lichtenstein assumed that the occurrence of a giant-cell tumour of bone in the vertebral column was rare and believed that many of the vertebral giant-cell tumours described in the literature were in reality aneurysmal bone cysts. The following clinical, radiological, gross pathological and histological characteristics have been advanced to distinguish between the two conditions. Age-Aneurysmal bone cysts occur chiefly in the young. Nine out of ten patients treated in the Mayo Clinics (McCarty, Dahlin, Doyle, Lipscomb and Pugh 1961) were from ten to fifteen years old, and Hess (1960) estimated that 75 per cent of patients were under twenty. Giant-cell tumours of bone tend to occur in older persons. Of Schajowicz’s (1961) eighty-five patients fifty-eight were aged between twenty and forty and only nine were aged between fifteen and twenty. In Williams, Dahlin and Ghormley’s (1954) series of 101 patients ninety-one were over twenty. In Mnaymneh, Dudley and Mnaymneh’s (1964) material the incidence in the second decade was relatively high-eleven out of forty patients. These statistics are of little value in individual diagnosis because aneurysmal bone cysts may occur in persons of over twenty and giant-cell tumours of bone have been reported in patients of under twentyeven, in one of Jaffe’s patients, at the age of ten. Localisation-In the long bones the position of an aneurysmal bone cyst is eccentric and it is typically seen in the metaphysial area, not extending into the epiphysial end of the bone, whereas giant-cell tumours of bone involve the epiphysial end and often invade the adjacent metaphysis. In the vertebral column there is no such difference in localisation. According to modern views vertebral giant-cell tumours are rare, and are most frequently found in the sacrum. Behaviour-An aneurysmal bone cyst is considered a benign lesion but recurrence and even extension of the lesion after incomplete removal have been reported (McCarty et a!. 1961, Donaldson 1962). Giant-cell tumours of bone show a great tendency to recurrence after incomplete removal, and about 10 per cent show a malignant evolution. McCarty and his colleagues stated that only two aneurysmal bone cysts reported had undergone malignant changes and that both