Cardiac myxoma with glandlike structures. An immunohistochemical study.

We report the case of a 14-year-old girl with a left atrial myxoma associated with atrial septal defect. Histopathologically, glandular structures were found at the base of the tumor. Immunohistochemical examination of the tumor revealed positive staining of the glands with cytokeratin, epithelial membrane antigen, and carcinoembryonic antigen. The positive staining for epithelial markers suggests that these structures are epithelial and could represent either endodermal heterotopia or multipotential mesoderm retaining the capacity for epithelial expression. The glands should not be confused with metastatic mucin-producing adenocarcinoma.