A 55 year old man presented with a scalp lesion. The initial diagnosis was a sebaceous cyst, and excision under local anaesthetic was planned, but the large size of the mass and the finding of bony fixation raised doubts. Cranial magnetic resonance imaging showed a giant intracranial parasagittal frontal tumour eroding through the top of the skull. The lesion was excised via a bilateral frontal craniotomy. Histological examination was consistent with meningioma, an entity known to cause bony erosion of the skull.

S J Griffiths, specialist registrar, G Wabwire, senior house surgeon, R M Redfern, consultant, N Powell, consultant neuroradiologist, department of neurosurgery, Morriston Hospital, Swansea SA6 6NL, D H Evans, general …