Congenital Midline Upper Lip Sinus: Case Report and Review of the Literature.

Congenital midline sinus of the upper lip are rare congenital malformations. We recently identified a case featuring a congenital midline sinus of the upper lip. The punctate opening was positioned at the midline of the philtrum, immediately below the base of the columella. Surgical removal of the sinus tract was conducted through an intraoral approach. Up to now, fewer than 70 cases have been reported. Several postulates, including the fusion theory, merging theory, and invagination theory, have been proposed to explain the formation of the congenital midline sinus of the upper lip. Nevertheless, the etiology of this uncommon abnormality remains unclear. This report details a case of a congenital upper lip sinus presenting as a congenital midline sinus of the upper lip and reviews the current literature on this condition.