Congenital median clefts of the upper lip.

This is a report of 12 cases of congenital median cleft deformity of the upper lip seen in the Department of Plastic Surgery, Singapore General Hospital. This deformity is extremely rare and there are probably not more than 100 cases reported in the literature. The classification, nomenclature, pathogenesis and embryological development of median clefts are still not clearly understood. An analysis of the 12 cases is made with the view to clarify the nomenclature and classification of median clefts. An attempt is also made to explain the embryogenesis of this deformity and its common association with cranial and other facial defects.