Haemangiomata of the placenta.

A series of six placental haemangiomata is described. Of these one was large and was associated clinically with hydramnios and premature labour. The remaining five were discovered in the course of a systemic examination of 500 unselected placentae. The literature on this tumour is reviewed and it is concluded that this is a very common lesion occurring in about 1% of all placentae. The tumour is probably hamartomatous in nature and is derived from primitive chorionic mesenchyme. Most tumours are small and intraplacental and are not associated with any clinical side effects. The comparatively small group of large haemangiomata do show an association with hydramnios, premature labour, low birth weight, foetal distress and, in a few instances, cardiomegaly in the infant.