Revista de citología e histología

Heterotopic Ossification with and without Neovascularization in Aortic Valves: A Histopathological Study

Abstract

Susumu Matsukuma, Ayano Koga, Hiroaki Takeo and Kimiya Sato

Heterotopic ossification can be found in neovascularized aortic valves with end-stage valvular disease, but its histopathological characteristics are not fully understood. The present study found ossification and neovessels in 21 (28%) and 54 (72%) of 75 surgically removed dysfunctional aortic valves, respectively; there was a significant association between them (P<0.001). Fatty bone marrow was found in 5 aortic valves (6.7%) and always contained neovessels. Neovessels could be divided into thick-walled, arteriole-like vessels (ThKA-Vs) and thin-walled, capillarylike vessels (ThNC-Vs). ThKA-Vs would be a hallmark of rheumatic disease, were always accompanied by ThNCVs, and were closely related to ossification (P=0.046). ThNC-Vs may be in part branches of ThKA-Vs, but were also identified in 23 aortic valves without ThKA-Vs. In 44 non-rheumatic dysfunctional aortic valves, such ThNC-Vs only were also associated with ossification (P=0.004). In addition, the present study revealed vessel-independent focal/ minute ossification without nearby neovessels in 6 dysfunctional aortic valves, and also in 4 of 75 age- and sexmatched postmortem non-dysfunctional aortic valves with no neovessels or prominent calcification/thickening; there were no significant differences in the incidence between them. Neovascularized vessels would consist of rheumatic neovessels (ThKA-Vs and their branches) and non-rheumatic neovessels (ThNC-Vs only), and the presence of neovessels is one of the risk factors for aortic valvular ossification. However, aortic valvular ossification can occur in various pathogeneses, such as rheumatic neovessel-dependent ossification, non-rheumatic neovessel-dependent ossification, and rarely vessel-independent focal/minute ossification.