Patterns of anomalies are categorized into four types based on developmental process. Which category describes a primary structural defect resulting from intrinsic developmental abnormalities?

• A. Malformation
• B. Deformation
• C. Disruption
• D. Dysplasia

Answer: (A)

Malformations are primary structural defects that arise from intrinsic abnormalities in embryologic development. They occur during tissue formation itself, so the abnormal architecture is present from birth due to morPHogenetic errors, not from external forces or later destruction. This makes them the best fit for a defect caused by intrinsic developmental abnormalities.

For context, deformations come from mechanical forces acting on normally developing tissue (like clubfoot due to uterine constraint), disruptions result from destructive events that damage tissue that was forming normally (such as amniotic bands), and dysplasias involve abnormal differentiation within a tissue leading to disorganized structure. Classic malformations include neural tube defects and certain congenital heart or facial formation defects, all rooted in abnormal morphogenesis.