Prenatal imaging diagnosis of PIK3CA‐related overgrowth spectrum disorders in first trimester with emphasis on extremities

Abstract

PIK3CA-related overgrowth spectrum (PROS) encompasses rare genetic disorders resulting from somatic mosaic gain-of-function mutation of the PIK3CA gene. Due to mosaicism, the clinical presentation is highly variable and includes CLOVES (congenital lipomatous overgrowth, vascular malformation, epidermal nevi, scoliosis/skeletal and spinal anomalies) syndrome, megalencephaly-capillary malformation syndrome (MCAP), fibroadipose hyperplasia or overgrowth, or Klippel–Trenaunay syndrome1. There is some degree of overlap of the clinical phenotypes between these entities encompassed by the term PROS1. We report a case of PROS diagnosed in the first trimester and describe the imaging findings, particularly anomalies of the extremities, which should raise the suspicion of this congenital spectrum, that is represented mainly by focal overgrowth. A 30-year-old Caucasian primiparous patient, without any relevant personal or familial history, was referred at 13.6 weeks of pregnancy due to cystic masses of the soft tissues. Sonographic examination showed increased cephalic biometry (head circumference, 125 mm; > 97th percentile) without underlying ventriculomegaly and with