[Clinical aspects and differential diagnosis of occipital bone processes]

Tumours and tumour-like processes of the cranial bones do not occur very frequently; 2.5 per cent of all bone tumours are found in the calotte. On the other hand, the pre-operative and operative error possibilities regarding these processes are considerable, leaving multiple bone metastases out of consideration. The situation is complicated by many processes in the vicinity of the bone which affect or alterate the bone secondarily. On the basis of two better known tumours, the giant cell tumour and the aneurysmatic bone cyst, the diagnostic possibilities and difficulties are discussed in greater detail. The value of computer tomography mainly consists in the exact localisation in the bone and the surrounding tissues. Scintigraphy, too, can yield valuable information. Since in these processes as well as some other tumours no advantages can be derived from an irradiation therapy, but induced malignisations are even possible after several years, radical surgery is the only therapy of choice that is left. Considerable difficulties may arise in this connection due to narrow relations to vessels and blood paths. Finally, the problems of a prognostic statement is dealt with because histologic examinations, for instance in case of giant cell tumours, cannot yield precise information either with respect to dignity. Some authors, therefore, classify the latter as potentially malignant tumours.