Background: Cardiac myxomas have varying clinical presentation, uncertain histogenesis, and debatable immunohistochemical profile. A few malignant cases have been previously reported.
Methods: Fifty-three consecutive cardiac myxomas were histologically investigated and results compared with clinical data. The main goal of the study was to investigate the immunohistochemical differentiation and the clinicopathologic correlations.
Results: Stromal cells were characterized by the expression of the von Willebrand factor endothelial marker (12 of 53 cases) and diffuse cytoplasmic neuropeptides such as protein gene product 9.5 (50 of 53 cases), S100 protein (47 of 53) and neuron-specific enolase (30 of 53), all of which were expressed in 30 (57%) of 53 tumors. Stromal cells did not show endocrine granules, epithelial, or smooth muscle immunoreactivity. Non-cardiac-related symptoms were observed in 7 of 53 patients and promptly disappeared after tumor excision; median values and percentages of total immunoreactivity scores for neuropeptides were higher in these 7 cases, but data analysis showed no statistical significance. Glands were detected in 2 myxomas, and they showed epithelial (cytokeratins and carcinoembryonic antigen), protein S100, and neuron-specific enolase immunoreactivity; this pattern has been previously detected in human gut. All tumors showed benign behavior, and no mitosis was detected.
Conclusions: The results of this study support the hypothesis that stromal cells originate from multipotent mesenchyme capable of neural and endothelial differentiation; rare myxoma glands would represent entrapped foregut rests. A correlation could exist between neuroendocrine differentiation and non-cardiac-related symptoms.