Myxoma refers to benign tumors and accounts for up to 50% of all primary neoplasms of the heart. Usually cases of myxoma as an independent disease are given. In the presented clinical case, left atrial myxoma was combined with lentiginosis: a lot of black papular rashes on the skin of the face, head, entire surface of the trunk and extremities, as well as black patches on the surface of the lips and a hamartoma polyp of the esophagus. These changes may be a manifestation of multiple hamartoma syndrome, which is a rarely diagnosed pathology. Another feature of the case is the onset of myxoma by the clinic of acute posterior myocardial infarction with ST segment elevation and pathological Q wave in a 29-year-old patient. According to coronary angiography, stenoses of the coronary arteries were not detected. A pronounced vasospasm of the left coronary artery was found. There was an increase in the level of lactate dehydrogenase 808.11 units/l and troponin I at admission up to 433.8 ng/ml, with an increase to 19 010 ng/ml. The given clinical example shows the importance of a comprehensive examination of patients with myxomas to exclude other hereditarily mediated syndromes, especially in the presence of skin pigmentation.