Eosinophilic myocarditis. Light micrograph (LM) of a section of heart muscle. Eosinophilic myocarditis is a rare and potentially lethal disease characterized by eosinophil ( a type of white blood cell ), infiltration of the myocardium. The association between eosinophilia and myocardial injury is well established and may present several etiologies, from hypersensitivity and autoimmune diseases to neoplasias and infections. Magnification: x 150 when printed at 10 centimetres wide. Human tissue