日本小児循環器学会雑誌 Pediatric Cardiology and Cardiac Surgery

Eosinophilic myocarditis (EMC) is a myocardial disease with a benign prognosis, for which patients are successfully treated by the early administration of steroids. To date, no studies have reported the occurrence of myasthenia gravis (MG) during tapering of the steroid dose. A 3-year-old girl was admitted to our hospital with pallor and in respiratory distress, which were not associated with an antecedent infection. Echocardiography displayed depression of the wall motion. We suspected EMC because of eosinophilia and increased cardiac enzymes after the initial steroid therapy, so steroid treatment was restarted. The cardiac wall motion improved thereafter, with a decrease in peripheral blood eosinophilic count. After discharge from our hospital, she developed gait difficulty with muscle weakness and right blepharoptosis, and after detailed examination, she was diagnosed with MG. She was treated with immunosuppressants in addition to steroids, and her MG symptoms disappeared. Thus, it is important to administer steroids at the early phase when EMC was suspected. MG related to an immunological mechanism may occur because immunity is involved in the onset of EMC. This case suggests attending to neurological symptoms during tapering of the steroid dose.