WBR0335

Author	[[PageAuthor::Yazan Daaboul, M.D. (Reviewed by Alison Leibowitz)]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Embryology, MainCategory::Fundamental Clinical Skills
Sub Category	SubCategory::Head and Neck
Prompt	[[Prompt::An 8-month-old boy is brought by his mother to the physician's office for a congenital facial abnormality that she wishes to be corrected. The patient's past medical history is significant for feeding difficulty and recurrent episodes of acute otitis media. Upon further questioning, the mother reports that the child is the product of an uncomplicated normal vaginal delivery. She admits to being non-compliant with her prenatal vitamins and to drinking alcohol during her pregnancy. A patient with a similar abnormality is shown in the image below. The physician explains that the boy has an embryological defect. Which of the following processes failed to occur in this patient? ]]
Answer A	AnswerA::Failure of fusion of the maxillary and medial nasal processes
Answer A Explanation	AnswerAExp::Cleft lip is characterized by the failure of fusion of the maxillary and medial nasal processes.
Answer B	AnswerB::Failure of fusion of the maxillary and lateral nasal processes
Answer B Explanation	AnswerBExp::Cleft lip is not characterized by the failure of fusion of the maxillary and lateral nasal processes.
Answer C	AnswerC::Failure of fusion of the mandibular and the medial nasal processes
Answer C Explanation	AnswerCExp::Cleft lip is not characterized by the failure of fusion of the mandibular and the medial nasal processes.
Answer D	AnswerD::Failure of fusion of the mandibular and the lateral nasal processes
Answer D Explanation	AnswerDExp::Cleft lip is not characterized by the failure of fusion of the mandibular and the lateral nasal processes.
Answer E	AnswerE::Failure of fusion of the maxillary and the palatine processes
Answer E Explanation	[[AnswerEExp::Although cleft palate frequently occurs with cleft lip, cleft palate is due to failure of fusion of the lateral palatine processes, the nasal septum, and the median palatine process. Failure of fusion of the maxillary and the palatine processes are not characteristic of either cleft lip or cleft palate.]]
Right Answer	RightAnswer::A
Explanation	[[Explanation::The patient is most likely presenting with a cleft lip (cheiloschisis), a common congenital malformation. Cleft lip is characterized by the failure of the maxillary and the medial nasal processes to fuse. On the other hand, cleft palate is characterized by the non-union of the lateral palatine processes, the nasal septum, and the median palatine processes. Typically cleft lip and cleft palate occur together although they result from different embryological pathophysiological processes. Although they may appear in isolation, CLP may be part of a cleft lip/palate ectodermal dysplasia syndrome (CLPED), which is characterized by the presence of hidrotic ectrodermal dysplasia, syndactyly, and mental retardation, along with cleft lip and palate. Patients with cleft lip and palate (CLP) often have facial deformation, associated with feeding difficulties, and recurrent infections of the middle ear. Although the real cause of cleft lip is still unknown, studies have shown an association between cleft lip and administration of high doses of steroids or anticonvulsant drugs, lack of vitamin supplementation, and alcohol intake early during pregnancy. Educational Objective: Cleft palate is characterized by the failure of fusion of the maxillary and the median nasal processes. References: Sarvraj SK, Virinder SK. A comprehensive review of the genetic basis of cleft lip and palate. J Oral Maxillofac Pathol. 2012; 16(1):64-72. First Aid 2014 page 90]]
Approved	Approved::Yes
Keyword	WBRKeyword::cleft lip, WBRKeyword::cleft palate, WBRKeyword::fusion, WBRKeyword::maxillary, WBRKeyword::lateral, WBRKeyword::palatine, WBRKeyword::facial abnormality
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::