Oncocytic variant of choroid plexus papilloma. Evolution from benign to malignant "oncocytoma".

Abstract

The case of a left temporoparietal choroid plexus papilloma in a 12-year-old girl, which recurred 12 months after subtotal resection and apparent full recovery, is described. The two consecutive surgical specimens were studied by light and electron microscopy. The first surgical specimen showed a tumor composed of cells with distended cytoplasm packed with numerous mitochondria characteristic of "oncocytic" change. Thus, tumor was the rare benign oncocytic variant of choroid plexus papilloma. A repeat histologic study of the recurrent tumor 12 months later showed evidence of malignant evolution in the form of multinucleated cells with frequent, often bizarre, mitotic figures. A rarely described oncocytic variant of choroid plexus papilloma that showed evidence of evolution from benign to malignant "oncocytoma" is discussed.