Are Papillary Adenomas Endolymphatic Sac Tumors?

Abstract

Papillary adenomas of the temporal bone have been considered as originating from the endolymphatic sac. The radiologic, surgical, and pathologic findings in a patient suffering from von Hippel—Lindau disease with bilateral papillary adenomas of the temporal bone cast some doubt on this site of origin. Radiologically, the center of tumor growth was at the top of the jugular bulb. Intraoperatively, the tumor was found to have reached the lateral wall of the endolymphatic sac, but the lumen was tumor-free. Both ciliated and nonciliated tumor cells were found in the resected tumor, resembling the ultrastructure of normal epithelial lining in the human mastoid. A strong positive immunohistochemical reaction for keratin and negative reactions for vimentin, glial fibrillary acidic protein, and S-100 protein in the tumor tissue of this patient are typical for middle ear mucosa. Therefore, the described papillary adenoma originated from the mucosa of the pneumatic spaces surrounding the jugular bulb, and the theory that the endolymphatic sac is the origin of all papillary-cystic tumors (adenocarcinomas) should be questioned.