Congenital Upper Lip Sinus.

Congenital upper lip sinus (CULS) is an extremely rare anomaly. The aim of the study is to present a new case and compile the present knowledge of CULS to help foster a deeper understanding of this disease. A 9-year-old girl with a midline CULS, a prolonged maxillary labial frenulum, and a palatal epulis is presented. Thirty-nine papers met the eligibility criteria and 45 cases were included in the systematic review. CULS shows typical clinical and pathologic characteristics. It tends to occur at the midline region horizontally (n=35; 78%) and the upper part of the white lip (n=23; 51%) vertically. No ethnic predilection is found, but it tends to show a female predilection (n=28; 62%). Twenty-six cases (58%) are symptomatic. Thirteen cases (29%) are accompanied by other maxillofacial defects. In all cases, the sinus was lined with stratified squamous epithelium. The etiology remains unknown but 3 theories have been put forward: the fusion theory, the merging theory, and the invagination theory. The authors believe that CULS shows homogeneity with cleft lip to some extent and maybe a microform of it. Primary treatment is surgical excision and the prognosis is favorable, with no complications or recurrence.