Epidermoid cyst with infiltrative malignant melanoma in the cerebellopontine angle.

We report a patient with an intracranial epidermoid cyst associated with malignant melanoma in the cerebellopontine angle. The CT, MRI and histopathological findings showed an intracranial epidermoid cyst with an adjacent infiltrating melanoma. Immunohistochemical staining of the solid tumour was positive for the melanoma marker HMB45 and negative for GFAP and cytokeratin. Both CT and MRI were helpful in this patient but the diagnosis could only be made on histopathology.