Congenital nephrosis of the Finnish type: overview of placental pathology and literature review.

Congenital nephrosis of the Finnish type (CNF) is a rare, autosomal recessive disorder of glomerular filtration that results in massive proteinuria, edema, and ascites. Although previous studies describe the classic renal lesions characterizing this disorder, there are few documenting in detail the associated placental alterations. In this context, we present a case of CNF with emphasis on the placental pathology and compare our findings to what has been previously reported in the literature. A 36-year-old G2P1 with no significant medical history developed persistently elevated amniotic fluid alpha-fetoprotein in the absence of neural tube defects. Because of a clinical suspicion of CNF, she electively terminated the pregnancy at 19 weeks. Postmortem examination revealed characteristic renal changes, confirmed by electron microscopy, as well as significant placental villous edema. Although the placenta was not enlarged, the villi appeared profoundly hydropic. Extensive cystic vacuolar change was documented in both stem villi and tertiary villi, affecting 95% of the villi present. Since the fetus was not grossly edematous, the placental findings may represent the first sign of systemic hypoproteinemia.