Salivary gland chorstoma of the middle ear

초록

Choristoma is a mass of tissue histologically normal for an organ of part of the body other than the site at which it is located. A salivary choristoma is an extremely uncommon tumor in the middle space. It appears to be developmental abnormalit and may be associated with abnormalities of adjacent structures. It ususally presents with unilateral conductive hearing loss which may be long-standing. We present a case of slaivary gland choristoma of the middle ear. The patient was 29-year-male. He suffered form right side conductive hearing loss for 10 years. The right tympanic membrane showed central perforation. Pure tone audiogram showed a conductive hearing loss of 60% on the left side. The temporal bone CT revealed an ovoid soft tissue mass (8mm in diameter)in the right middle ear. It extended from tympanic membrane to oval window area. Operating finding revealed the incus body and long process were necrotic and dislocated. Facial nerve showed dehescence. There were an ovoid mass at the second genus and tympanic segment of facial nerve. The mass was removed under the impression of facial nerve neuroma. The microscopic finding showed small polypoid mass covered by stratified cylindrical respiratory type epithelium. The mass showed a lobulated normal salivary gland. The glands are formed by acinar structere lined by pyramidal epithelial cell having basal nuclear and abundant acidophilic granular cytoplasm. There was no salivary excretory duct.