A second case of "chorangiocarcinoma" presenting in a term asymptomatic twin pregnancy: choriocarcinoma in situ with associated villous vascular proliferation.

We report a case of "chorangiocarcinoma" (choriocarcinoma in situ in association with a villous vascular proliferation) presenting in one of dichorionic diamniotic twin placentae at term in an asymptomatic pregnancy. This case is the second reported of chorangiocarcinoma in the literature and the first case of choriocarcinoma (in situ or otherwise) in a twin pregnancy. The lesion had the gross appearance of an infarct in the presenting twin placenta. Histologic sections revealed malignant villous trophoblast in eight microscopic fields within the placental infarct. The remainder of the placenta and that of the cotwin were normal. The mother and infants had no evidence of metastatic disease 3 months postpartum. This placenta is the fourth example in the English literature of isolated choriocarcinoma in situ.