Myocardial Infarction Due to Coronary Thromboarteritis, Following Acute Febrile Mucocutaneous Lymph Node Syndrome (MLNS) in an Infant

Abstract

A previously healthy 6-month-old male infant was admitted to our clinic for persistent high fever and an erythematous skin rash. Hyperemia of conjunctivae, redness of oral mucosa, and swelling of several cervical lymph nodes were also observed. Soon after admission he developed jaundice which continued for one week. Results of laboratory examinations revealed leukocytosis, elevated ESR, mild proteinuria, leukocytes in urinary sediment, hyperbilirubinemia, increased serum alpha-2-globulin and positive CRP. Serum ASO titer was less than 100 Todd units and complement fixation reactions for various viruses were not significant. Cultures of blood, urine, stool and throat were negative. He was treated with antibiotics and steroids and improved gradually, but then developed signs and symptoms of congestive heart failure. An ECG showed a pattern of extensive myocardial infarction. He died of congestive heart failure at the age of 21 months. Autopsy findings revealed focal aneurysmal dilatation and obstruction of the bilateral coronary arteries. The myocardial infarction involved the septum of the anterolateral wall of the left ventricle. The coronary arteries, distal aorta, iliac arteries and pulmonary arteries were also involved, but very slightly. The symptoms, laboratory findings and the course of this patient were compatible with those of acute febrile mucocutaneous lymph node syndrome (MLNS), MLNS has been accepted as a new syndrome by most Japanese pediatricians in recent years. Its etiology is still unknown. Some of the patients with this syndrome had died suddenly of coronary thromboarteritis after recovering from the acute illness. Although autopsy findings of the fatal cases have been similar to those describing infantile polyarteritis nodosa, the relationship between MLNS and infantile polyarteritis is controversial.