Dermoid tumour of the fourth ventricle with hyperdense aspect demonstrated on CT scan. Case report.

The authors describe the case of a 37-year-old patient, who, after a minor craniocerebral trauma suffered in 1970, was admitted to hospital because of progressive headache, unsteady gait and balance disturbances, deglutition disorders and diplopia. Computed tomography (CT) scan showed a large median hyperdense tumour of posterior fossa with the fourth ventricle involvement. Operation under microscope was performed to remove a considerably large cystic tumour, occupying the fourth ventricle and cisterna magna, displacing the cerebellar lobes and pushing the vermis upward. The tumour was waxy and grey, whereas the cystic liquid had the colour and consistency of oily fluid. The capsule was occluded with the CO2 laser. Postoperative course was good.