Intracranial germinoma in the pineal region arising after subtotal resection of epidermoid cyst: case report.

We present an unusual case of a germinoma of the pineal region arising adjacent to an epidermoid cyst in a 16-year-old male. Initial imaging findings were classic for epidermoid cyst. The patient underwent two partial resections at an outside institution, each specimen demonstrating pure epidermoid cyst. Follow-up imaging over a period of 24 months showed an area of progressive contrast enhancement adjacent to the initial lesion, suggesting the development of a neoplasm. Given the area of contrast enhancement in addition to worsening headaches and visual changes, he underwent a third and final resection at our institution. Pathology revealed a mixed germ cell tumor with prominent germinoma component in addition to a well-differentiated epidermoid cyst. Details of his imaging and pathologic findings are presented, and possible explanations for these findings are explored, the most likely of which is lack of complete resection at the onset failed to identify the whole of the neoplasm. We conclude that pediatric epidermoid cysts of the pineal region should always receive close follow-up, particularly when total resection is not performed.