Placenta in chronic herpesvirus infection: morphological changes and perinatal outcomes

High prevalence of herpes-virus infection among women of reproductive age and the possibility of latent persistence with subsequent reactivation highlight the importance of studying the morphological changes in the placenta that arise when infected with herpes simplex viruses (HSV) types 1 and 2. This article provides a morphological characterisation of placental alterations in herpesvirus infection and their association with the development of perinatal pathology in the fetus. Microscopic features that allow suspicion of herpetic placental involvement are described: chronic villitis, intervillositis, vasculitis, focal villous necrosis, trophoblast destruction, damage to Kachchenko–Hofbauer cells, and formation of giant multinucleated cells with viral inclusions (Cowdry type B HSV cells). Differences between HSV-1 and HSV-2 are analysed with respect to the severity of inflammatory-destructive and vascular changes, as well as the clinical consequences of intra-uterine infection. A greater neurotropism and propensity for generalised infection of HSV-2 compared with HSV-1 is noted. The review was prepared using publications indexed in international and Russian scientific databases, including PubMed, eLibrary and Google Scholar. Search terms included: herpetic placentitis, intervillositis, funiculitis, placental pathomorphology, fetoplacental insufficiency, association with perinatal pathology and their combinations in Russian and English.