Failure of proper or normal development; more specifically, a primary structural defect that results from a localized error of morphogenesis; e.g., cleft lip. Cf. deformation.
Arnold-Chiari m. malformed posterior fossa structures resulting from caudad traction and displacement of the rhombencephalon caused by tethering of the spinal cord; may or may not be accompanied by spina bifida and associated anomalies such as meningomyelocele; weak evidence of autosomal recessive inheritance.Arnold-Chiari deformity, Arnold-Chiari syndrome, cerebellomedullary malformation syndrome;
cystic adenomatoid m. a rare developmental lung-bud abnormality which results in stillbirth, acute progressive respiratory disease of newborns, or protracted childhood pneumonias; this m. combines features of a hamartoma, dysplastic growth, and tumorous growth. Three types have been described, based chiefly on cyst diameters: Type I: up to 10 cm; Type II: less than 1.2 cm; Type III: less than 0.5 cm.
Browse Medical References: