Klippel-Trenaunay-Weber syndrome involving fetal thigh: prenatal presentations and outcomes.

Objectives: We analyzed the prenatal presentations and perinatal outcomes of Klippel-Trenaunay-Weber syndrome involving fetal thigh in order to provide relevant information for prenatal counseling.
Methods: We reviewed our own cases and searched for cases from Medline that met the criteria of Klippel-Trenaunay-Weber syndrome involving fetal thigh. Those with isolated hemangioma, hemangioendothelioma, and hemangiolymphangioma were excluded.
Results: The cases of Klippel-Trenaunay-Weber syndrome involving fetal thigh, totaling 21, were collected for analysis. These included 19 cases from Medline search and two cases from our institution. The cases with lesions involving right thigh, left thigh, and both thighs were 12:8:1. The gender of affected fetuses was 9 male, 9 female, and 3 unknown. Among the 21 cases, 6 fetuses (28.57%, 6/21) had isolated thigh lesions, and the other 15 cases (71.43%, 15/21) had extensive lesions involving pelvis, abdomen, retroperitoneum, or thorax. Prenatal presentations varied with hypoechoic cystic mass with limb asymmetry, 95.23% (20/21); polyhydramnios, 38.09% (8/21); cardiomegaly, 19.04% (4/21); thick placenta, 9.52% (2/21); nonimmune hydrops fetalis, 9.52% (2/21); and oligohydramnios, 4.76% (1/21). Ten cases (47.62%, 10/21) underwent termination of pregnancy. For those who continued with pregnancy, the rate of complications with Kasabach-Merritt syndrome was 36.36% (4/11) and the mortality rate in the neonatal period was 45.45% (5/11). The causes of neonatal mortality in these five cases included consumption coagulopathy (Kasabach-Merritt syndrome), cardiac failure, sepsis, and prematurity.
Conclusions: Klippel-Trenaunay-Weber syndrome involving fetal thigh is rare. Our review showed that the location of involvement on the right thigh is more than on the left. Males and females were equally affected. Nearly three fourths of the cases had extensive involvement over other parts of the body. Prenatal ultrasound finding of a raised thigh mass of significant size and limb asymmetry were the most important features. The mortality rate was as high as 45.45% in the neonatal period.