Petrified cardiac myxoma masquerading as organized atrial mural thrombus.

To our knowledge, petrified cardiac myxoma is a heretofore undescribed histologic variant of atrial myxomas. It is an obsolescent myxoma that has been converted to a sclerosiderotic nodule by impregnation of the tumor's stromal connective tissue fibers with iron, calcium, and ceroid pigments, presumably following recurrent hemorrhage in the myxoma over time. Four cases of this unusual histologic variant of cardiac myxoma were identified from among 22,150 autopsies performed over the 25-year period, 1954 through 1979. These four cases were asymptomatic incidental postmortem findings discovered in two men (54 and 82 years of age) and two women (66 and 80 years of age). The original autopsy diagnoses of the left atrial lesions were fibrosiderotic nodule (Gamna-Gandy body) in one patient and organized mural thrombi in the other three patients.