alobar holoprosencephaly - Humpath.com - Human pathology - Photos - pictures

In alobar HPE, the brain consists of a single spherical forebrain structure with a single ventricle. A large cyst which communicates with the ventricle is present in the posterior-dorsal part of the brain. Alobar HPE is incompatible with survival.

The brain in alobar HPE is small and the gyral pattern and cortical architecture are abnormal. The eyes, which evaginate from the forebrain in the fourth week, are small and malformed or there is only one eye (cyclopia).

Because the olfactory nerves which are part of the rhinencephalon are absent, the term arrhinencephaly has also been applied to this malformation. However, in alobar HPE, there is much more missing than the olfactory brain.

The brain malformations are accompanied by severe midline facial anomalies (holoprosencephaly sequence).

Synopsis

cerebral anomalies

small single forebrain ventricle
no interhemispheric division
absence of olfactory bulbs and tracts
absence of corpus callosum
non separation of deep gray nuclei

severe facial dysmorphism

proboscis (a trunk-like structure above the single eye)
exophtalmy
hypotelorism

nasal malformations

single nostril
arhinia

facial clefts

medial cleft lip
medial cleft palate
medial nasolabiopalatal cleft

midline skeletodental anomalies (malformations of midline structures anterior to the sella turcica comprising suture development and cartilage development)

partial absence of the intermaxillary suture (in the region anterior to the central incisor)
absence of the internasal suture
partial absence of the metopic suture (caudal part)
single midline nasal bone
midline maxillary central incisor
short nasal septum
absence of crista galli
partial absence of cartilaginous tissue anterior to the sella turcica

endocrine dysgenesis

absent pituitary gland
hypoplastic adrenal glands
micropenis

Case records

Case #12063: Isolated alobar holoprosencephaly
Case #13535: Associated alobar holoprosencephaly