Prenatal Diagnosis of Fetal Trisomy 5 Mosaicism with Congenital Pulmonary Airway Malformation Type 3: A Case Report.

Background: Trisomy mosaicism of chromosome 5 is uncommon with few cases described. Case report: A 41-year-old woman underwent ultrasound (US) at 16 weeks, which showed oligohydramnios and intrauterine growth restriction (IUGR). Amniocentesis discovered a karyotype of 47,XX,+5/46,XX. US at 19 weeks disclosed IUGR, enlargement of right side of heart, main pulmonary artery dilatation, and a suspected congenital pulmonary airway malformation (CPAM) in the inferior lobe of the left lung. Due to poor fetal prognosis, the parents opted for legal termination of pregnancy. At postmortem, a wide ventricular septal defect and CPAM type 3 were found. Cytogenetic analyses on fetal tissues detected mosaic trisomy 5 in skin, thymus, kidneys and CPAM. Placenta and fetal peripheral blood revealed normal female karyotype. Discussion/conclusion: These results suggest that if a fetus presents normal phenotypic features, mosaicism may be confined to extraembryonic structures, otherwise, in case of malformations, it may be carried by affected organs.