[Epidermoid cyst of the oral floor with massive deposition of melanin in the cystic epithelium].

Dermoid cyst or epidermoid cyst of the oral cavity usually occurs in the floor of the mouth. We encountered a 21-year-old woman who had developed epidermoid cyst in the oral floor. Since infancy she had been aware of a swelling in the oral floor. Recently, the swelling began to grow larger gradually. The lesion was excised under general anesthesia by intraoral approach. The swelling was spherical in shape, measured 50 x 45 x 40 mm in size, and weighed 40 g. Histopathological examination revealed keratinized, stratified squamous epithelium on the cyst wall and marked deposition of melanin at the base of the epithelium.