title: Midline sinus of the upper lip and a theory concerning etiology.
abstract: A rare case of midline upper-lip sinus, without associated congenital anomalies, is presented. Etiopathogenesis between cleft central upper lip and central philtral sinus differ. Therefore, several theories for etiology are discussed, and a more plausible theory of epidermal burrowing and invagination is presented.
mesh_terms: D000328:Adult; D006801:Humans; D008046:Lip / Q000002:abnormalities* / Q000196:embryology / Q000601:surgery; D008297:Male