A case of carcinoid tumor of the middle ear.

We report here a case of a carcinoid tumor observed in the middle ear (ME), which was initially diagnosed as ME adenoma. The patient was a 64-year-old woman who was first seen in our hospital in March 2001 for a 7-month hearing loss. On otoscopic examination, a whitish mass could be observed through the intact tympanic membrane. High-resolution computed tomography demonstrated a tumor-like lesion in the ME with no evidence of bone destruction. A myringotomy and biopsy were performed and an initial diagnosis of ME adenoma was made. Light microscopy showed fragments of cellular tissue in which both glandular (adenomatous) and trabecular (carcinoid) growth patterns could be identified, but neuroendocrine differentiation was not detected by immunohistochemistry (negative staining for chromogranin A and synaptophysin). On the basis of this diagnosis, the patient underwent a tympanomastoidectomy in June 2001, in which the presumed ME adenoma was completely excised and the diagnosis was modified to ME carcinoid tumor. Immunohistochemical examinations at that time showed positive staining of the tumor cells for chromogranin A and synaptophysin. This case suggests the difficulties in distinguishing ME carcinoid tumors from ME adenomas. The patient is without recurrence of her disease to date.