A case of congenital mucous cyst of the lower lip

We encountered a case of congenital mucous cyst of the lower lip. At birth, the patient was found to have a slightly protruding mass with a pinhead-sized surface on the mucosa of the right lower lip. We diagnosed a congenital mucous cyst.The patient was a 4 -month-old girl who presented with a mass on the right lower lip. No tooth eruption was observed in the oral cavity. A globular pedunculated mass, approximately 5 mm in diameter, was detected on the mucosa of the right lower lip, and the cyst was excised. Her postoperative progress has been good, with no signs of recurrence.Histopathological examination revealed a cyst lined with the stratified squamous epithelial cells that formed the surface layer. The cyst wall was clearly observed. The wall was not composed of epithelial tissues, but of histiocytes, fibloblasts, capillaries, and fibrous connective tissue. These findings suggested that the mucous cyst wall.