Basal plate plaque: a novel organising placental thrombotic process

In contrast to thrombi and haematomas at other body sites, thrombi in the placental intervillous space are not traditionally known to undergo organisation. This report presents 11 examples of a form of organising thrombotic process that develops as a plaque on the foetal aspect of the basal plate. Originally identified in the placenta of a foetus showing severe intrauterine growth restriction, further examples of this lesion, which we term a 'basal plate plaque', show a spectrum of placental involvement. Small lesions appear to occur at points of localised stasis at the basal plate (eg, at edges of anchoring villi or in small basal plate depressions). Large areas of involvement, as seen in the original case, may be pathological markers of more generalised disturbances in placental circulation or of hypercoagulability in the intervillous space. Large basal plate plaques may therefore prove to be diagnostically significant and should be reported.