Persistence of Nuchal Edema and Distended Jugular Lymphatic Sacs in Noonan Syndrome

Abstract

Objective: Noonan syndrome is one of the most common genetic syndromes manifesting at birth. Still, it is diagnosed late, often during infancy. Diagnosis is difficult because prenatal ultrasound findings are unspecific and the dysmorphias after birth can be subtle. Cases: Two women were referred to our university hospital because of an increased nuchal translucency in the first trimester of pregnancy. Further ultrasound examination showed the bilateral presence of distended jugular lymph sacs. Karyotyping revealed euploidy in both fetuses. The second trimester ultrasound scan showed a persistence of the jugular lymph sacs together with a nuchal fold, indicating a disturbed lymphatic development. There were no other anomalies. In 1 case the jugular lymph sacs containing newly formed lymph node tissue remained visible until 35 weeks’ gestation. Both newborns were diagnosed with Noonan syndrome after birth. Postnatal echocardiography revealed a mild pulmonary stenosis. Conclusion: Distension of the jugular lymph sacs is known to cause nuchal edema and normally resolves after the first trimester. In case of persistence of the jugular lymphatic sacs beyond the second trimester of pregnancy, the diagnosis of Noonan syndrome and subsequent DNA testing should be considered.

A normal 20‐week scan of a euploid fetus with a history of first‐trimester increased nuchal translucency: caution or reassurance?

“…Consequently, anomalies can be missed and diagnosed only after birth. Specifically, mild cardiac anomalies such as pulmonary stenosis in Noonan syndrome, are often missed on ultrasound21. Also, one third of the genetic syndromes did not show any potentially detectable ultrasound signs in the study of Bilardo et al 20, which is in agreement with the findings of other studies6, 17, 19.…”

Targeted ultrasound examination and DNA testing for Noonan syndrome, in fetuses with increased nuchal translucency and normal karyotype

“…In the presented cases we show that suspicion of Noonan syndrome should arise when, after an increased NT, ultrasound investigation in the second trimester shows a persistant NF or cystic hygroma in combination with at least one of the following features: hydrops fetalis, pleural effusion, cardiac anomalies, polyhydramnios or specific facial abnormalities (Table 1) (Witt et al, 1987;Benacerraf et al, 1989;Izquierdo et al, 1990;Sonesson et al, 1992;Nisbet et al, 1999;Achiron et al, 2000;Bradley et al, 2001;Menashe et al, 2002;Witters et al, 2002;Eccles et al, 2003;Gandhi et al, 2004;Ragavan et al, 2005;Schluter et al, 2005;Becker et al, 2007;Bekker et al, 2007;Kiyota et al, 2008;Gonzalez-Huerta et al, 2010;Houweling et al, 2010). Heart anomalies are found in 60-70% of the postnatal cases (mostly pulmonary stenosis, ASDS and hypertrophic obstructive cardiomyopathy) and will be one of the major causes requiring medical attention (Sharland et al, 1992;Allanson, 1993).…”

Perinatal features of the RASopathies: Noonan syndrome, Cardiofaciocutaneous syndrome and Costello syndrome

“…The mechanism of hypoglycemia in CS is not completely understood; though hyperinsulinism and deficiencies of growth hormone and cortisol have been reported [Gregersen and Viljoen, ; Alexander et al, ; Barreca et al, ]. Hypotonia was relatively specific to CS and CFCS; however, it was also repeatedly observed in NS [Chrzanowska et al, ; Achiron et al, ; Grebe and Clericuzio, ; Kaji et al, ; Van den Bosch et al, ; Bekker et al, ; Gripp et al, ; Armour and Allanson, ]. Similarly, our data suggest that increased fetal and neonatal weight may be more common in CS; however, they are also observed in NS and CFCS.…”