Answer: Atherosis of decidual vessels

Histology: Within the decidua attached to the placenta, the decidual arterioles show foci of fibrinoid necrosis of their wall. Other decidual vessels show an accumulation of foamy macrophages. These are the changes of a decidual necrotizing vasculopathy.

Discussion: Lysosomal storage diseases are typically associated with the presence of foamy vacuolization of the stromal cells and trophoblastic cells of the placenta. Acute inflammation of the decidua is often seen in association with acute chorioamnionitis, but can also be seen in term deliveries as a normal finding particularly when it is mild.

Atherosis is most often related to pregnancy-induced hypertension/preeclampsia, but may be associated with hypertensive crises from underlying medical disorders such as systemic lupus erythematosis. In such circumstances, other tests (e.g., renal biopsy) may be needed to make this distinction.