McKusick-Kaufman syndrome: the difficulty of establishing a prenatal diagnosis of an uncommon disorder.

Prenatal evaluation of abdominal cystic masses can be complex and challenging. We report the case of a fetus with a large cystic abdominal mass and discuss how the differential diagnosis was narrowed to include McKusick-Kaufman syndrome (MKS). MKS is characterized by the triad of postaxial polydactyly, congenital heart disease, hydrometrocolpos, and genital malformations in males. Rare conditions such as MKS are difficult to diagnose prenatally and require postnatal phenotyping and molecular studies before a definitive diagnosis can be established.