Amniochorial Membrane Nodules

  • Jerzy Stanek


Four lesions, amnion nodosum (AN), squamous metaplasia of amnion (SM), vanishing twin (VT) and yolk sac remnant (YSR), are discussed. AN is a hallmark of severe oligohydramnios, commonly seen in fetal congenital malformations, prolonged premature rupture of membranes or maternal vascular malperfusion, particularly of postterm pregnancy. It is associated with a high perinatal mortality. Grossly, it features shiny nodules on the placental membranes, fetal surface of the chorionic disc or the umbilical cord. Microscopically, AN are nodules of fetal vernix attached to the amniotic surface. The differential diagnosis includes mainly SM. Histological diagnosis of AN should warn of the possibility of congenital anomalies, particularly of the urinary tract, if unknown at the time of birth. SM are patches of keratinizing squamous epithelium on the amniotic surface that cannot be easily wiped out. Its significance is that SM must be differentiated from AN, candida infection and subchorionic fibrin deposits, but by itself it does not have clinical significance. VT is a nodule present in the membranes or less commonly on the placental disc representing an embryo that died in the first trimester. YSR is a well-demarcated calcified embryonal rest on the chorionic disc or placental membranes.


Amnion nodosum Amnion Oligohydramnios Congenital malformations Squamous metaplasia Vanishing twin Yolk sac remnant Placenta 


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© Springer Nature Switzerland AG 2019

Authors and Affiliations

  1. 1.Division of PathologyCincinnati Children’s Hospital Medical CenterCincinnatiUSA

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