label: Endolymphatic sac tumor
label_lc: endolymphatic sac tumor
description: A low-grade papillary epithelial neoplasm (adenocarcinoma) with a slow growth pattern. The endolymphatic duct emerges from the posterior wall of the saccule (of the inner ear) and ends in a blind pouch, the endolymphatic sac. Endolymphatic sac tumors (ELSTs) are known under different names in the literature (Heffner tumor, aggressive papillary middle ear tumor, and low-grade adenocarcinoma of endolymphatic sac origin).