Low-grade adenocarcinoma arising from the endolymphatic sac is an uncommon
tumor that is characterized clinically by hearing loss and radiologically b
y temporal bone destruction. The authors report a case of low-grade adenoca
rcinoma of endolymphatic sac origin that mimicked a posterior fossa meningi
oma in both clinical and neuroimaging examinations. In this case, the most
unusual and interesting feature was the lack of auditory symptoms and tempo
ral bone destruction. The lesion occurred in a 21-year-old man who presente
d with headaches that had been increasing in frequency for 6 months and was
associated with blurring of vision, diplopia, occasional nausea and vomiti
ng, and gait disturbance. On examination, this patient exhibited bilateral
papilledema, left sixth cranial nerve palsy, and gait ataxia. Neuroimaging
studies revealed a large right posterior fossa tumor. At surgery, a hemorrh
agic papillary adenocarcinoma of endolymphatic sac origin was found.