A case of achondrogenesis type IA with an occipital encephalocele.

We report on a case of achondrogenesis type IA (Houston-Harris) with an occipital encephalocele. Prenatal sonograms revealed polyhydramnios, subgaleal edema, microcephaly, a narrow thorax, pericardial effusion, and a severe short-limbed dwarfism with unossified tubular bones and vertebral bodies. Postmortem examination demonstrated additional findings of hydrops fetalis, a membranous calvarium with a defect, an occipital encephalocele, hypoplastic lungs, and wedge-like tubular bones. Whole body radiography revealed no ossification of the bones except some small identified foci of calcification in the base of the skull, clavicles, and pelvic bones. Histological examination of the growth plate showed hypercellularity and enlarged vacuolated chondrocytes with PAS-positive diastase-resistant cytoplasmic inclusions. Various abnormalities have been reported in association with achondrogenesis type IA, however, an associated neural tube defect has not previously been described in the literature. We report on an infant with both of these disorders.