Symptomatic neuroepithelial (colloid) cysts of the third ventricle. A unique case report in nontwin brothers.

Colloid cysts are relatively rare benign tumors comprising less than 2% of all intracranial mass lesions. However, since the advent of computed tomography of the head, these tumors are being recognized more frequently, occasionally before their symptomatic presentation. Much controversy remains as to the true cells of origin and pathogenesis of these cysts. Although a neuroepithelial origin has become increasingly accepted, Rathke cleft cysts, ectopic respiratory tissue, and other endodermal sources have been postulated. The first familial occurrence in middle-aged identical twin brothers was cited recently in the literature. Described here are the first reports of symptomatic colloid cysts in two nontwin brothers, lending further support to the potential for genetic expression of neuroepithelial cysts. Also included are preoperative computed axial tomographic images, histopathologic photomicrographs with case descriptions and comparisons, and suggestions to elucidate further the development and presentation of colloid cysts.