[A Case of Malignant Transformation of Epidermoid Cyst with Cerebrospinal Fluid Dissemination]

Primary Intracranial Malignant Epidermoid with Multiple Metastases in Internal Organs: A Rare Autopsy Case

Primary intracranial malignant epidermoids are rare, with most cases developing from a pre-existing benign epidermoid cyst. We report a case involving a rare autopsy finding of a primary intracranial malignant epidermoid in the brainstem with cerebellopontine angle (CPA) involvement. A 53-year-old woman with double vision was diagnosed with right abducens palsy. At her visit to our hospital 3 months after the onset of the first symptom, she presented left hypoglossal nerve paralysis and truncal ataxia in addition to right abducens palsy. Magnetic resonance imaging (MRI) revealed a mass lesion (2-cm long and 3-cm thick) in the left CPA that exhibited gadolinium enhancement. Moreover, gadolinium-enhanced magnetic resonance imaging (MRI) revealed abnormal multiple brainstem and supratentorial mass lesions with partial enhancement. Whole-body computed tomography failed to identify any possible primary lesion. Following a tentative diagnosis of an epidermoid cyst with an assumption that the tumor was highly aggressive, we performed subtotal surgical resection of the CPA tumor. Histological findings revealed a malignant epidermoid in the CPA lesion. Although the patient underwent radiation and chemotherapy after the surgical resection, she died of respiratory failure 10 months after the onset of symptoms. Herein, we report the rare clinical course and autopsy data, and discuss the characteristic features of this rare condition.