[The coincidence of Paget's disease and an immunoblastic sarcoma (author's transl)].

Malignant change is to be expected in about 1% of patients with Paget's disease. Usually these are osteosarcomas. Fibrosarcomas, benign and malignant giant cell tumours and chondrosarcomas are less common. The present case concerns the development of an immunoblastic sarcoma in the humerus, which was affected by Paget's disease. Only one other similar case is recorded in the literature. Other myelogenous tumours, such as plasmocytomas, are very rare in association with Paget's disease. Consequently there is no evidence for a causal connection between Paget's disease to these tumours, whereas sarcomas arising from bine tissue may be regarded as a form of malignant degeneration of Paget's disease.