Eosinophilic Myocarditis: A Rare Histopathological Finding and Diagnostic Challenge in Sudden Cardiac Death

Background: Eosinophilic myocarditis (EM) is a rare inflammatory myocardial disorder that may cause arrhythmia, heart failure, cardiogenic shock, or sudden cardiac death. Objectives: To describe the forensic and histopathological findings of a fatal case of EM and emphasize appropriate interpretation of pathological diagnosis, mechanism of death, and underlying etiology. Methods: A forensic autopsy and histopathological examination were performed in a 48-year-old man who died suddenly without documented preceding cardiac symptoms. Results: Autopsy revealed cardiomegaly, myocardial discoloration and necrosis, intracavitary mural thrombi, and no significant macroscopic coronary stenosis. Histopathology demonstrated myocyte degeneration and necrosis with dense eosinophil-rich inflammatory infiltration accompanied by lymphocytes, neutrophils, histiocytes, and hemorrhagic foci. These findings strongly supported EM as the principal pathological diagnosis. However, the etiology remained undetermined because complete toxicological, hematological, parasitological, autoimmune, and immunohistochemical investigations were not documented. A fatal arrhythmia was considered a plausible mechanism of sudden death but was not directly demonstrated. Conclusions: This case highlights the importance of integrating autopsy and histopathological findings while distinguishing pathological diagnosis, probable mechanism of death, and etiological classification in sudden death associated with EM.