Papillary tumor of the temporal bone.

Papillary tumors of the middle and inner ear have been interpreted histogenetically in many ways. In 1989 Heffner proposed the endolymphatic sac epithelium as a possible origin. These rare tumors are clinically aggressive and can cause extensive temporal bone destruction. Because of this behavior, endolymphatic sac tumors (ELST) were classified as low-grade adenocarcinomas, although metastasis has not yet been documented. Two papillary neoplasms of the temporal bone are presented, which we believe are examples of adenomatous tumors arising from the epithelium of the endolymphatic sac. One was associated with a pituitary adenoma. A third case of a papillary middle ear neoplasm is described that shows histologic features similar to the other two, but it was located in the tympanum and had no connection to the endolymphatic sac. This report focuses on clinical, radiologic, and histologic findings of papillary tumors of the temporal bone with additional emphasis on modern concepts of histogenesis and aspects of differential diagnosis.