[Case of recurring middle ear adenoma]

We report a case of recurring middle ear adenoma with bone formation that was histologically difficult to differentiate from adenocarcinoma. The patient was a 31-year-old female. Preoperative clinical and CT findings in the 31-years-old woman examined suggested benign tumor of the middle ear. Although intraoperative pathological examination indicated adenocarcinoma, tympanoplasty in canal reconstruction was done. Malignancy was not considered because the tumor had not increased in size for 1 year and no bone erosion had occurred in the ossicles or middle ear cleft. The definitive pathological diagnosis was middle ear adenoma. The tumor repeatedly recurred thereafter, closely resembling normal middle ear mucosa and making it difficult to remove completely. When middle ear adenoma is suspected, surgical procedures should be determined carefully based on radiological and intraoperative findings in tumor expansion.