To elucidate the histogenesis of cardiac
myxomas, the literature has been reviewed, including all previous immunohistochemical studies, and an extensive immunohistochemical study of 19 cardiac
myxomas has been undertaken with
antibodies to
factor VIII,
desmin,
vimentin,
myoglobin,
cytokeratin (CAM 5.2 and AE1/AE3), and
S100 protein. In all cases,
vimentin stained endothelial as well as "
myxoma" (stromal) cells. In contrast,
factor VIII only stained endothelial cells. In 16 cases,
desmin stained cells in the vascular structures; in 5 cases,
desmin stained
myxoma cells. In 6 cases,
S100 protein stained the
myxoma cells strongly.
Myoglobin was absent in all cases. In 1 case, CAM 5.2 and AE1/AE3 stained glandular structures. The results indicate the following: that most cardiac
myxomas are true
neoplasms derived from "embryonal rests"; that the various mesenchymal cells found in cardiac
myxomas (
myxoma cells, endothelial cells, smooth-muscle cells, fibroblasts, myofibroblasts, and chondroid cells), express differentiation, not histogenesis; that, apparently, only the
myxoma cells are neoplastic; and that the glandular structures infrequently found in cardiac
myxomas originate from entrapped foregut rests.