Non-exophytic Lambl excrescences of aortic valves: a morphological study

To elucidate the histopathological findings of classical Lambl excrescences (LEs) and non-exophytic LEs (non-ex LEs) without excrescent papillary features.

We examined 126 aortic valves (AVs) and revealed LEs (non-ex and/or classical), non-ex LEs and classical LEs in 106, 78 and 88 AVs, respectively. The detection of non-ex LEs was challenging, but elastica van Gieson stain highlighted their presence. Non-ex and classical LEs chiefly involved the ventricular regions, favoured posterior cusps and coexisted in the same areas of 31 AVs. A possible transformation of classical LEs into non-ex LEs was suggested histologically in 39 AVs. Non-ex LEs were associated with age of >70 years (P < 0.001) and marked deformity (P = 0.007). Classical LEs were associated inversely with marked deformity (P < 0.001), but not with age of >70 years. Compared with age- and sex-matched control AVs, non-ex LEs and marked deformity in dysfunctional AVs were more common (P = 0.037 and P < 0.001, respectively), but classical LEs were less common (P = 0.021).

Non-ex LEs have subtle features but are a common form of LEs, and seem to develop from classical LEs. AV dysfunction-related marked deformity can promote non-ex LEs.