Primary monomorphic adenoma of the middle ear.

The benign, monomorphic adenoma, derived from the respiratory epithelium of the middle ear, is a well circumscribed, greyish, avascular tumor. Its histology--documented by light and electron micrographs contained in this report--supports a distinct entity and pathogenesis apart from the malignant adenocarcinoma. Utilizing two case reports, this compendium emphasizes the clinical presentations, as well as radiographic and audiometrical characteristics, of the tumor. The first case represents the typical tumor with conductive hearing loss. The second case is the first reported facial paralysis associated with hemorrhagic infarction of an adenoma which was reversible by surgical resection of the tumor. Based on the histology and four year postoperative follow-up, the authors conclude the adenoma may be effectively managed by surgical resection.