Duplications of organs and/or tissues are rare in morphogenesis and have frequently been attributed to incomplete twinning. To further elucidate the phenotypes associated with organ duplications, we present three infants with duplication of the pituitary gland (DPG). A review of previously reported cases with DPG showed that the commonest additional findings were hypothalamic enlargement, a broad or duplicated sella, cleft palate, hypertelorism, oropharyngeal tumors, agenesis or hypoplasia of the corpus callosum, and abnormalities of vertebrae. DPG and additional malformations constitute a distinct and recognizable pattern of anomalies, which may constitute a polytopic field defect due to splitting of the notochord. However, the precise inductive mechanism resulting in DPG remains unknown.
(c) 2005 Wiley-Liss, Inc.