Intervillous Space: Infiltrates
Histological lesions involving the intervillous space include inflammatory and infectious diseases covered elsewhere, maternal malignancies, maternal haematological disease and trophoblastic lesions including choriocarcinoma. Placental involvement by maternal malignancies is uncommon, but likely under-reported as the lesions often are not visible on macroscopic examination, and may mimic infarcts or other benign lesions such as perivillous fibrin with intermediate trophoblast. Mostly they arise from haematogenous spread, but direct tumour extension is also reported. Malignant melanoma is the most common tumour to spread, followed by lung and breast cancer and leukaemia/lymphoma. Maternal metastasis involves the intervillous space and, in a small proportion of cases, chorionic villous invasion with or without vascular invasion is also present. Fetal/infant metastasis is rare. Malignant tumour cell spread to the conceptus has to be compared to the increasing recognition of the role of two-way benign cell transfer causing microchimerism of the mother and fetus in both maternal and childhood diseases. A number of cases with placental metastases appear associated with stillbirth due to many possible causes but only rarely due to fetal metastases.
KeywordsMaternal malignancy Placental metastasis Fetal metastasis Intervillous space Chorionic villi Malignant melanoma Leukaemia Maternal cancer
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