Papillary Neoplasm of the Endolymphatic Sac: A report of two cases

ABSTRACT

Papillary tumor of the temporal bone or middle ear has been recognized as an aggressive neoplasm because of its invasive growth pattern. The site of origin is controversial so that most cases have been reported under various diagnostic terms. Recently, Heffner(1989) suggested that the endolymphatic sac is a possible site of origin, because the tumor resembles the endolymphatic sac in several aspects. We report two such cases. One patient was a 34-year-old female presenting with tinnitus and hearing difficulty for 1 year. Temporal bone CT revealed extensive bone destruction by the tumor which was located in the posterolateral aspect of temporal bone. The other patient was a 56-year-old female who complained of tinnitus, dizziness and otalgia for 2 years. Cranial MR imaging showed an irregularly marginated mass in the left jugular fossa with extension to the petrous bone. Histologically, both cases showed a papillary pattern and locally destructive growth that are typical of papillary tumor of the endolymphatic sac. The papillae were lined by a single layer of bland-looking cuboidal to low columnar cells. Immunohistochemically the lining cells expressed cytokeratin, epithelial membrane antigen, neuron specific antigen and in one case, S-100 protein, supporting the thesis that these neoplasms might be of endolymphatic sac origin.