Characteristics of Clinical and Imaging Findings of Epidermoid Cysts under the Skin of the Mental Region

Abstract

Epidermoid cyst often arises in the floor of oral cavity; however, it is relatively rare to arise subcutaneously in the mental region. We reported characteristics of clinical and imaging findings of epidermoid cysts under the skin of the mental region. The patient was a 53-year-old male. He complained of a subcutaneous mass without pain in the left mental region. A palpable soft and movable thumb-sized mass without pain was observed at the first examination. Ultrasound examination revealed a well-demarcated mass with heterogenous hyper-echoic internal echo and posterior echo enhancement. On power Doppler sonography, a small amount of blood supply was found around the periphery of the mass. Plain CT scan revealed a globular soft-tissue mass with peripheral high and central low CT values area. The mass was removed under local anesthesia using intraoral approach. A histopathologic diagnosis was epidermoid cyst. Recurrence is not observed 2 years after surgery. There were only 3 reports of epidermoid cysts in the mental region, including our case in Japan, clinically characteristics of age ranging 20 to 66 years of age and the mean age of 46 years, with 2 males and 1 female. The size was from 20 mm to 12 mm in diameter and from the tip of a thumb up to the tip of a small finger. Ultrasound images of the inside of epidermoid cysts that we experienced this time showed enhancement of relatively uniform hyperechoic image and posterior echo, which was characteristically slightly different from findings of epidermoid cysts generally reported.