Animal: Cat, foetus at day 40 of gestation, female.
Diagnosis: Head, face: diprosopus of the mid face with double meningoencephalocele
Description: The feline foetus was aborted at day 40 of gestation. The central parts of the face were developed in duplicate. The upper lips and the nose were present twice, but there was only one oral cavity. In addition the cat had a duplicated meningoencephalocele.
Comments: Diprosopus, also called craniofacial duplication, is an extremely rare congenital disorder whereby parts or the entire face are duplicated. Recent studies suspect the protein Sonic Hedgehog (SHH) to be relevant in the development of this malformation. The protein plays a critical role in patterning of the mediolateral axis of the mid and upper face. A transient loss of SHH signalling produces a collapse of the facial midline, a condition called hypotelorism which can result in cyclopia. In reverse, excess SHH leads to a mediolateral frontonasal widening of the face, known as hypertelorism, which can cause facial duplication. Diprosopus is often accompanied by other congenital disorders, particularly neuronal and cardiac malformations.
Picture by: Phillip Olias, Department of Veterinary Pathology, Freie Universität Berlin, Germany
Author: Marie-Charlotte von Deetzen, Department of Veterinary Pathology, Freie Universität Berlin, Germany