Middle Ear “Adenoma”: a Neuroendocrine Tumor with Predominant L Cell Differentiation

This morphological and immunohistochemical study demonstrates that tumors currently known as null ear adenomas are truly well-differentiated epithelial neuroendocrine tumors (NETs) composed of cells comparable to normal intestinal L cells, and therefore, these tumors resemble hindgut NETs. These tumors show consistent expression of glucagon, pancreatic polypeptide, PYY, and the transcription factor SATB2, as well as generic neuroendocrine...