DNA ploidy and proliferative index of cardiac myxoma.

Cardiac myxoma is the commonest tumour of heart. The histogenesis of this lesion is controversial as its origin has often been debated between the thrombogenic and neoplastic theories. We analysed DNA ploidy and proliferation indices of 30 cardiac myxomas which include 25 sporadic and five familial cases by image cytometry and proliferating cell nuclear antigen immunostaining. Of the 25 cases, 18 were aneuploid, three diploid and four tetraploid. Four of the five familial cases including the recurrent lesions were aneuploid. Poor tissue preservation precluded ploidy analysis in one familial case. The proliferation index of the sporadic cases ranged from 0.4 to 36.1 percent. The familial cases showed proliferation index between 10.2 and 22 percent. In addition to cardiac myxoma, proliferation index was assessed in 10 cardiac thrombi where it ranged from three to 58 percent. This study suggests that cardiac myxoma can be best interpreted as a neoplasm with a slow growth potential.