Beckwith–Wiedemann syndrome in association with posterior hypoplasia of the cerebellar vermis

Abstract

We present the case of a 28-year-old woman with an unremarkable medical and obstetrical history. Both parents are Caucasian; the couple is not consanguineous and have already had a healthy child after a normal pregnancy. The first ultrasound scan at 13 weeks was considered normal. Second trimester serum markers suggested a chromosomal abnormality risk of 1/108, leading to another diagnostic ultrasound at 18 weeks, which identified an omphalocele. Karyotype analysis of the fluid sampled by amniocentesis was normal, 46, XX. The 22-week ultrasound confirmed the omphalocele. The latter contained only the small bowel, and its collar measured 20 mm. The liver was in a normal position. In addition, the fourth ventricle was open, communicating with the cisterna magna through a large canal, with hypoplasia of the posterior vermis (Figure 1). No facial anomaly was noticed. A multidisciplinary group of staff explained the poor prognosis of these morphological abnormalities to the couple, whose request that the pregnancy be terminated was approved in accordance with French law. At 25 weeks, a 1040-g female fetus (95th percentile for term) was delivered. The subsequent pathology examination confirmed the features we had observed and also showed craniofacial dysmorphy involving macroglossia, large ears with indentation of the left lobe, and a marked under-eye crease, together with organomegaly. The placenta was hypertrophic and dysmature, with heterogeneous villi. Microscopic analysis highlighted cytomegaly of the extravillous placental trophoblast cells and the fetal adrenal cortex. The association of these anomalies led to a diagnosis of Beckwith–Wiedemann syndrome (BWS). Subsequent