Epithelial-myoepithelial carcinoma of external auditory canal evolving from pleomorphic adenoma

Abstract

A 45-year-old female patient visited the clinic due to ear fullness. A 8 mm sized mass was found in the external auditory canal. It was surgically removed and the pathology exam confirmed epithelial-myoepithelial carcinoma (EMC). EMC is glandular epithelial neoplasm of the salivary gland. EMC originating from the external auditory canal is very rare, and only 1 case has been reported so far in the literature. The difference between our case and the one previously published was that the tumor was previously proven as a benign tumor (i.e. pleomorphic adenoma) 5 years ago. Therefore, this is the first case in the literature showing the evolvement of pleomorphic adenoma of the external auditory canal into EMC.

Keywords: Epithelial-myoepithelial carcinoma; External auditory canal cancer.

Fig. 1

Preoperative temporal bone CT, endoscopic image and pure tone audiogram. A 8×6 mm sized mass lesion was identified in the right superior external auditory canal. A minimal air-bone gap was identified on the pure tone audiogram.

Fig. 2

Histologic findings of the epithelial myoepithelial carcinoma. The tumors are pathologically characterized by two types of cells, showing low-cuboidal and dark epithelial cells in the inner rows or parts of the nests (A) and polygonal, plump and clear myoepithleial cells in the outer parts (B). Carcinoembryonic antigen (CEA) is an epithelial marker (C) and S-100 protein is a myoepithelial marker that highlights the cytoplasms of the tumor cells with myoepithelial differentiation (D).

Fig. 3

A month after mass excision, IAC MRI T1, T1 enhance, endoscopic image and PET-CT. A 5×6 mm sized non-enhancing soft tissue lesion was identified in the right superior external auditory canal. Little evidence of significantly focal hypermetabolic lesion around right external auditory canal. IAC MRI: internal auditory canal magnetic resonance imaging, PET-CT: positron emission tomography computed tomography.

Fig. 4

After modified lateral temporal bone resection operation temporal bone CT, endoscopic image and pure tone audiogram. Wound healed well and there was no evidence of tumor recurrence at 6-month follow up. Also, hearing was preserved.