Epithelial tumors of the middle ear--are middle ear carcinoids really distinct from middle ear adenomas?

Primary tumors of the middle ear are much less commonly encountered in clinical practice than non-neoplastic lesions such as inflammatory polyps (aural polyps) or cholesteatomas. The rarity of such tumors can complicate attempts, by both clinicians and pathologists, to correctly classify them. It has been customary for many authors to segregate middle ear adenomas (MEAs) from middle ear carcinoids as two discrete benign neoplastic entities. It has become apparent, however, that MEAs and carcinoids of the middle ear share a sufficient number of overlapping pathologic features and similarities of clinical behavior to warrant their collapse into a single diagnostic category. It is proposed that these tumors should be designated as MEAs, which are defined as benign, indolent epithelial tumors of the middle ear that do not invade or erode bone and do not metastasize. The individual tumor cells are cytologically bland and polygonal, columnar or plasmacytoid-shaped; they may be arranged in islands, glandular formations or trabeculae, but not in papillary structures. They are typically keratin- and vimentin-positive immunohistochemically, and are often positive as well with antibodies for chromogranin A, synaptophysin, neuron-specific enolase, Leu-7, serotonin, pancreatic polypeptide and S-100 protein. Dense core neurosecretory granules may be identifiable by electron microscopy. Conservative surgical excision is the treatment of choice, and local recurrence following complete excision is quite uncommon.