[An autopsy case of primary cerebellar-pontine angle epidermoid carcinoma]

A 65-year-old man developed right facial palsy and six months later experienced sudden unconsciousness and right hemiplegia. On admission he had severe nuchal rigidity, decreased visual acuity, and a hearing disturbance. A CT scan and angiography failed to reveal any lesions in the brain, but CSF cytology showed undifferentiated malignant cells with a high level of neuron-specific enolase. A postcontrast CT scan and MRI demonstrated diffuse meningeal enhancement and a faintly rim-enhanced cystic lesion at the cerebellopontine angle. The patient died four months after admission, and postmortem examination revealed meningeal dissemination of squamous cell carcinoma, probably arising from an epidermoid cyst at the cerebellopontine angle. Microscopic examination revealed squamous epithelial debris and a foreign body reaction in portions of the cyst wall and in the surrounding subarachnoid space near the base of the cyst. Rim enhancement of the cyst on MRI and the microscopic findings indicated that the recurrent headaches may have been the result of chemical aseptic meningitis caused by spontaneous leakage of the cyst's contents.