Prenatal Sonographic Diagnosis of Klippel-Trenaunay Syndrome With a Dandy-Walker Variant: Expanding the Prenatal Anomaly Spectrum

Klippel-Trenaunay syndrome (KTS) is a rare and clinically significant congenital disorder involving vascular and tissue malformations. Its prenatal diagnosis is extremely difficult but feasible with high-resolution ultrasonography (US). A case study is provided of KTS, in a multigravida patient. The prenatal US revealed a multilocular cystic lesion with some areas showing monophasic venous flow, in the fetal retroperitoneum, with extension into the pelvic cavity, into both lower limbs, as well as limb hypertrophy. The gestational age of the fetus corresponded to 17–18 weeks. Dysmorphic features and some additional neurological findings were also seen in the fetus, raising suspicion of a genetic syndrome. This case highlights classic KTS findings of limb hypertrophy, vascular malformations, and skeletal changes identified prenatally. Although KTS is not typically linked to genetic abnormalities, overlapping phenotypes with other overgrowth syndromes may indicate complex genetic or mosaic conditions. The early diagnosis of fetal KTS, with US, provides an important diagnostic role in multidisciplinary clinical management and parental counseling.