Bone formation in cardiac valves: a histopathological study of 128 cases.

In a series of 1,177 patients with surgical valve resection, there were 128 (10.9%) patients with the histological finding of bone and/or cartilage formation (bony metaplasia; heterotopic ossification) in the excised valve (119 aortic, 9 mitral). The incidence was higher in men (12.8%) than in women (8.5%). The bony metaplasia was always associated with valvular calcification. The metaplastic changes were encountered in all types of calcific aortic valve disease (senile, bicuspid valve, post-rheumatic). The marrow of the heterotopic lamellar bone was mostly composed of adipose tissue. Frequently, it showed chronic inflammation with polyclonal plasmocytic infiltration. Complete haematopoiesis was present only rarely.