Fine Needle Aspiration Cytology of Metastatic Endolymphatic Sac Tumor: A Case Report

Endolymphatic sac tumors are uncommon, slow growing, and locally aggressive neoplasms that arise within the endolymphatic sac, most commonly the intraosseous portion located in the temporal bone. There are only three previous cytology reports, and no prior FNAs have been reported. We present a case of a metastatic sporadic endolymphatic sac tumor, a phenomenon that has yet to be described on FNA and has only been previously reported once in cerebrospinal fluid cytology. We described the cytologic features on fine needle aspiration cytology and correlated the cytologic findings with the follow-up surgical resection of the metastatic focus.