Adenoma versus carcinoid tumor of the middle ear: a study of 48 cases and review of the literature.

Carcinoid tumors and adenomas of the middle ear are rare neoplasms of indeterminate relationship to one another. Indeed, the literature is devoid of a large comprehensive series that evaluates the clinical, histologic, and immunophenotypic features of these tumors and their potential relationship. Forty-eight cases of middle ear adenoma between 1970 and 1995 were identified in the files of the Armed Forces Institute of Pathology. All cases were evaluated for cytomorphology and architectural pattern, in addition to their reactivity with various immunohistochemical reagents. Clinical follow-up was also obtained. A comprehensive review of the literature was performed with an eye toward correlating any distinct differences or similarities between carcinoid tumors and adenomas of the middle ear. The patients included 21 women and 27 men, aged 20 to 80 years (mean, 45.0 y). Patients experienced hearing loss, mass, and/or pain for a mean duration of 1.7 years. The mean tumor size was 0.8 cm, with six tumors extending beyond the middle ear. Histologically, the tumors were moderately cellular and unencapsulated, arranged in glandular, trabecular, and solid patterns composed of small cells with "salt and pepper" nuclear chromatin distribution. The tumor cells were immunoreactive with keratin, keratin 7, chromogranin, and human pancreatic polypeptide. All patients had surgery. No patients died with their disease (mean follow-up, 15.7 y). Eight patients developed recurrences that were treated surgically and were without evidence of disease at last follow-up (mean, 15.1 y). Our study and the review of the literature showed adenomas and carcinoid tumors of the middle ear to be essentially indistinguishable benign tumors. Middle ear adenoma most correctly describes their morphologic features and clinical behavior, although neuroendocrine adenoma of the middle ear may be a more accurate designation.