GIANT CELL MYOCARDITIS: AUTOPSY CONFIRMATION OF A DIAGNOSTIC DILEMMA - A RARE CASE REPORT

Abstract Introduction/Objective Giant cell myocarditis (GCM) is a rare and rapidly progressive form of myocarditis, commonly leading to fulminant heart failure (HF), refractory ventricular arrhythmias or conduction system abnormalities and carrying a high mortality rate without prompt treatment. Due to its rarity, there is limited data on its prevalence, although studies show an incidence of 0.007–0.053% among autopsied cases. This entity primarily affects the heart, exhibiting a rapid clinical course and a poor prognosis necessitating immunosuppressive therapy and, in most instances, heart transplantation to improve survival rates. Methods/Case Report We present a case of a 62-year-old male with a prior history of complete heart block status post permanent pacemaker placement, presenting with acute decompensated heart failure. Laboratory investigations revealed elevated cardiac troponin levels (>35000) with echocardiography showing a reduced ejection fraction of 25% and an initial diagnosis of non-ST elevation myocardial infarction (NSTEMI) was made. Endomyocardial biopsy revealed GCM. Despite aggressive management, including immunosuppressive therapy and mechanical circulatory support, his condition deteriorated rapidly, leading to multiorgan failure and eventual death. The diagnosis was confirmed on autopsy. The diagnostic challenge of GCM lies in its clinical or pathologic overlap with other myocardial disorders such as cardiac sarcoidosis, viral myocarditis, and cardiac amyloidosis. Endomyocardial biopsy (EMB) remains the gold standard for diagnosing this entity which is characterized by a widespread inflammatory cell infiltrate with multinucleated giant cells in association with myocyte damage. The etiology of GCM remains unclear, but it is believed to be immune-mediated, possibly triggered by an autoimmune response. Results (if a Case Study enter NA) NA Conclusion Pathologists should give importance to consider GCM in the differential diagnosis of patients presenting with acute heart failure refractory to standard therapy. Early recognition and prompt initiation of immunosuppressive therapy are crucial for improving outcomes in patients with GCM. Awareness of this entity is crucial to make a timely diagnosis.