Central Neurocytoma and Epidermoid Tumor Occurring as Collision Tumors: A Rare Association

Abstract

<p>Different brain tumors of distinct histology can co-exist in the setting of phakomatoses or as a complication of radiotherapy. In the absence of these predisposing factors, this phenomenon is uncommon. When the lesions are in close proximity they are described as collision tumors and are extremely rare. A 58-year-old woman presented with persistent headache and cognitive decline for three months. Magnetic resonance imaging revealed a tumor arising from the atrium of the left lateral ventricle with heterogeneous contrast enhancement. This intraventricular lesion was adjacent to another extensive infiltrating tumor of the basal cisterns. Operative findings revealed a vascular ventricular tumor and gross total resection was achieved. An adjacent avascular basal cistern tumor with a pearly white sheen was encountered and partial excision was performed. The histopathological diagnosis was central neurocytoma and epidermoid tumor. There is only one documented description of a central neurocytoma co-existing with a tumor of different pathology. To our knowledge, this is the first reported collision tumor case involving central neurocytoma. Since the incidence of both lesions co-existing juxtaposed is extremely low, a chronic oncogenetic inflammatory process stimulated by the epidermoid tumor to the subventricular region is suggested. Other mechanisms for tumor collision are discussed and we suggest a classification system for this rare association to reflect their pathogenesis.</p>