Neuropathology : official journal of the Japanese Society of Neuropathology
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A malignant component in an epidermoid cyst is rare. We report an exceptionally rare case of a malignant melanoma arising in an epidermoid cyst located in the cerebellopontine (CP) angle. A 26-year-old woman presented with headache, vomiting, ataxia and difficulty in swallowing over the previous 3 months. ⋯ A very aggressive fulminant course of the disease was evident after surgery for the epidermoid cyst. Treatment options are limited. Criteria for identification of malignancy in an intracranial epidermoid cyst were identified in our case retrospectively and have been highlighted.
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Intracranial epidermoid cysts are rarely known to increase in size over a brief period. While malignant transformations of epidermoid cyst have been previously described, no reports to date have described rapid proliferation accompanied by mature hair follicles and sebaceous glands without malignant transformations. The present case involved a 71-year-old man who visited a local physician with disturbance of equilibrium. ⋯ Tumor recurrence was observed and was removed again in November of the same year. Intraoperative findings revealed a tumor that was primarily ochre-colored, non-shiny, brittle and suckable. The histopathological diagnosis was folliculosebaceous epithelial proliferative lesion accompanied by an epidermis-like epithelium and a differentiation into hair follicles and sebaceous gland,s and the tumor was determined to be an epidermoid cyst with proliferative folliculosebaceous epithelium.