Simultaneous occurrence of a congenital lateral upper lip sinus and congenital gingival cyst: a case report and discussion of pathogenesis.

The simultaneous occurrence of a congenital lateral sinus of the upper lip and of a congenital gingival cyst in a newborn boy is reported. The sinus extended to a depth of 10 mm and was lined by a parakeratinized squamous epithelium. The gingival cyst appeared as a 1 cm palatal enlargement lingual to the maxillary alveolar ridge and demonstrated a thin epithelial lining with localized plaquelike thickenings and occasional clear cells with vacuolated cytoplasm. There was no familial history of congenital deformities, and no additional abnormalities were noted. These two epithelium-lined structures show a clear topographic and morphologic relationship, and they may share a common embryologic origin. It is suggested that they derive from epithelium remaining subsequent to the union of the maxillary process and medial nasal process mesoderms.