Malignant Transformation of an Intracranial Extradural Epidermoid Cyst into Squamous Cell Carcinoma Presented with Cerebrospinal Fluid Leakage.

We report a case of malignant transformation of an intracranial extradural epidermoid cyst into squamous cell carcinoma (SCC), that presented with cerebrospinal fluid (CSF) leakage at the time of recurrence. Intracranial epidermoid cysts are histologically benign and slow-growing neoplasms. They are congenital lesions that develop from ectodermal remnants during neuroembryogenesis. Malignant transformation of epidermoid cysts into SCC is very rare. Various clinical presentations of these tumors after malignant transformation are mentioned in the literature. None of the previous cases, presented with CSF leakage as the recent case did. In cases of malignant transformation, surgical resection and then adjuvant radiation therapy are highly recommended.