A Case of Ectopic Endolymphatic Sac Tumor Occurring in the Middle Ear

Endolymphatic sac tumors (ELISTs) are rare, locally aggressive tumors that typically arise in the petrous portion of the temporal bone, often presenting with hearing loss, tinnitus, and vertigo. Here, we report a 57-year-old female presenting with ear-fullness and a reddish mass in the middle ear, which was initially suspected as a glomus tumor, with no other symptoms. Imaging showed no characteristic bone erosion, and as it was difficult to diagnose pathologically, the diagnosis of ectopic ELIST was made based on clinical evaluation. This unusual case of an ectopic ELIST confined to the middle ear suggests that these tumors can occur outside their conventional location, underscoring the need for their inclusion in the differential diagnosis of middle ear neoplasms and for further research into their pathophysiology and origins.