A malformation is best described as which of the following?

• A. A primary structural defect due to intrinsic developmental process
• B. A deformity due to external forces
• C. A defect due to disruption after birth
• D. A dysplasia of tissue

Answer: (A)

A malformation is a primary structural defect that arises from abnormal morphogenesis during embryonic development, due to intrinsic developmental factors such as genetics or early teratogenic influences. This means the anomaly is present because the structure did not form correctly in the womb. It’s different from a deformation, which is a normal structure distorted by external mechanical forces after formation; from a disruption, which is damage to tissue that was already forming; and from dysplasia, which is abnormal organization or differentiation of cells within a tissue. For example, a cleft lip/palate is a malformation because it reflects an intrinsic failure of proper fusion during development.