Review Question - QID 217678

This patient has a cleft lip with an intact palate; this is caused by the failure of maxillary prominence to fuse with the intermaxillary segment.

Cleft lip is a congenital craniofacial deformity that has not only cosmetic but also speech and swallowing consequences. Normally, the nose and lips form between weeks 3 and 6 of gestation. They arise from the lateral nasal processes, the medial nasal processes, and the maxillary processes. The alae develop from the lateral nasal processes while the nasal tip, philtrum, columella, and premaxilla develop from the medial nasal processes. The medial processes coalesce to form the intermaxillary segment and then fuse with the lateral nasal processes. Cleft lip can be complete or incomplete. The former has total separation of the lip and nasal sill. The latter still has an intact nasal sill. Regarding its epidemiology, cleft lip is twice as common in Asians (2/1000 births) compared to Caucasians (1/1000 births) and more common in men than women. Risk factors include maternal malnutrition, phenytoin, isotretinoin, and alcohol exposure in utero. Surgical correction is recommended between 3 and 5 months of age.

Figure A demonstrates a young patient with unilateral incomplete cleft lip.

Kelly et al. performed a population-based cohort study exploring the benefits of folic acid in preventing oral clefts. Given the demonstrated effectiveness of folic acid in preventing neural tube defects, interest developed regarding folic acid's potential impact on cleft lips and palates. In a cohort of 11,134 9-month-old infants, the authors found that infants had higher odds of developing cleft lip/palate in mothers who did not take folic acid during the first 3 months of pregnancy (odds ratio of 4.36). These data suggest that folic acid may play a role in preventing cleft lip and palate.

Incorrect Answers:
Answer 1: Complete failure of palatine shelf fusion leads to complete cleft palate. Embryologically, the palate develops following the lip. The medial nasal processes fuse at the midline and become the primary palate. The medial portions of the maxillary processes form the lateral palatine shelves, which fuse to form the secondary palate. Since the patient did not have any abnormalities within his mouth, he has an intact palate.

Answer 2: Distortion of the white roll and vermillion border causes an occult cleft, also known as a microform cleft. It can appear as a vertical scar of the upper lip. The white roll is the upper ridge of the lip skin and the vermillion border is the pigmented portion of the lip. Falling in the category of incomplete cleft, occult clefts are the mildest version of cleft lips. However, given the potential involvement of the orbicularis oris, speech and swallowing can still be affected; patients should be carefully examined. This patient has a cleft lip of greater severity.

Answer 3: Failure of palatine shelf fusion posterior to the incisive foramen leads to an incomplete cleft palate, which only involves the secondary palate. The palate develops from the primary and the secondary palates. The 2 palates come together at the incisive foramen, with the primary palate in front. As the patient lacked any deformities within the oral cavity, this patient does not have an incomplete cleft palate.

Answer 4: Failure of soft palate muscle fusion leads to a submucosal cleft palate, which is a subtype of cleft palates. Unlike other types of cleft palate, submucosal cleft palate has mucosa overlying the palatal defect, which can lead to a missed diagnosis. Signs of submucosal cleft palate include a notch in the hard palate, tissue translucency along the soft palate, as well as a split uvula. Given the unremarkable oral cavity, it is unlikely the patient has a palatal defect.

Bullet Summary:
Cleft lips are caused by the failure of the maxillary prominence to fuse with the intermaxillary segment.