A bone tumour of intermediate grade malignancy in the skull is describ
ed. These tumours are extremely rare and share several histological fe
atures with the benign osteoblastomas and low grade osteosarcomas. The
y may be associated with local invasion and pulmonary metastases. Trea
tment of this tumour in the skull poses several problems in view of it
s proximity to the cerebral cortex.