OBJECTIVETo investigate the clinical and pathologic features of middle ear adenoma (MEA).

METHODSEight cases of MEA were collected from Beijing Tongren Hospital, Capital Medical University between 2004 and 2014, and immunohistochemical staining was performed.

RESULTSThe patients included five women and three men (mean age, 37.5 years; median 37 years; range, 21-51 years). All patients had unilateral lesions. Five MEA occurred on the left side, and three on the right. In seven patients the MEA was primary, and they presented with hearing loss (6 cases), tinnitus (5 cases), sense of ear blockage (3 cases), otalgia (1 case) and facial nerve paralysis (1 case). The remaining patient had recurrent MEA, and presented with otorrhea, aural fullness and tinnitus. Histologically, the tumor cells were arranged in a variety of patterns, including solid sheets, nests, glands, ribbons or trabeculae. Glandular structures were prominent in one case only. Immunohistochemically, the tumor cells were diffusely positive for keratin (8/8) and vimentin (8/8), and focally positive for CK 7(8/8) and CK5/6(8/8). CK7 and CK5/6 were predominantly positive in tumor cells with glandular growth pattern; CK7 was positive in the luminal cells while CK5/6 was positive in the abluminal cells. Both were also expressed focally in scattered tumor cells with non-glandular pattern. The tumor cells were also diffusely positive for synaptophysin(8/8), diffusely but weakly positive for NSE (5/8), and were diffusely or focally positive for chromogranin A (4/8). Both S-100 protein and calponin were negative in all cases. The proliferation rate was low, about 1%-2%. Six cases were followed up for one year and three months to ten years and six months, with an average follow-up period of four years and two months. Two patients developed recurrence, but there were no regional or distant metastases.

CONCLUSIONSDiagnosis of MEA requires pathologic confirmation since the clinical symptoms are non-specific. MEA can show a variety of histologic patterns, and should be distinguished from other space-occupying lesions at this site. Immunohistochemical staining has greatly contributed to the diagnosis and differential diagnosis of MEA. The prognosis of this tumor is good. Patients with MEA require long-term follow-up for recurrences.