EP07.35: Prenatal ultrasound characteristics of fetal Cowden syndrome: a case report

Cowden syndrome is a rare autosomal dominant disorder with a prevalence of approximately 1/200,000. It is a rare autosomal dominant disorder characterised by mutations in the PTEN gene, whose loss of function contributes to tumourigenesis. Cowden syndrome presents with a variety of clinical manifestations, notably overgrowth, multiple misshapen tumours, and multiorgan tumours. A 32-years-old woman, gravida 1, para 0, came to our institution for prenatal diagnosis. Non-invasive prenatal testing results were low risk. A level 3 ultrasound at 33 weeks of gestation revealed: fetal biparietal diameter, head circumference and abdominal circumference were greater than 4SD; cardiothoracic ratio was enlarged, amniotic fluid was increased and the umbilical vein was widened in the abdominal cavity. A heterogeneous mass of 96*64mm with predominantly low to moderate echogenicity was seen in the liver with streak-like blood flow signals, and a hepatic tumour was considered. Genetic testing at 32 weeks of gestation suggested a PTEN gene variant [NM_000314.4:c.193T>G(p.Tyr65Asp)], which can cause Cowden syndrome. After termination of pregnancy, autopsy pathology diagnosed fetal organ overdevelopment and hepatic hemangioma. This article focuses on the prenatal ultrasound phenotype and genetic features of Cowden syndrome to increase clinicians' awareness of this rare disease. Genetic counselling should be recommended if both fetal overgrowth and tumour-like lesions are found. Diagnosis of the missense tumour syndrome can be made by molecular genetic testing that reveals heterozygous pathological variants of PTEN. Prenatal testing for the next pregnancy can be performed once the PTEN pathologic variant has been definitively identified in a preexisting patient.