The attached lesion was removed from the left atrium of a 66-year-old woman.
Cardiac myxomas can be heterogeneous under the microscope. They are said to arise from pluripotent mesenchymal stem cells, which means that they can undergo somatic differentiation. Their diagnostic cell, the lepidic (myxoma) cell, has basophilic cytoplasm with long processes, and bland ovoid nuclei. Classically, they form vasotropic rings around the small vessels within the tumor.
Because these tumors can be present for months to years prior to resection, they can undergo calcification. Also, depending on their location, they can be prone to hemorrhage from turbulent blood flow and contact with nearby endocardium. As the hemorrhage breaks down, it can deposit on fibrous and elastic tissue (along with calcium) to form so-called Gamna-Gandy bodies. These are most commonly seen in the spleen (same pathophysiology) but may also be seen in myxomas.