Giant cell myocarditis: Clinical and pathological features in an Indian population

Background: Giant cell myocarditis (GCM) is a rare disorder that is known primarily from North American, European, and Japanese case series. The clinical and pathological features of GCM in India have not been reported. Methods: We reviewed the pathology records from 1994 to 2010 from a tertiary care referral hospital in Mumbai for all cases of pathologically confirmed GCM. Gross and microscopic histological features and clinical characteristics of the GCM cases were described and qualitatively compared to GCM case series from other regions of the world. Results: The 12 cases of GCM constituted 0.005% of all autopsies and 0.8% of myocarditis cases. Gross pathological features included variably dilated chambers in 8/12 cases with multifocal involvement of the myocardium. Three had regional hypertrophy associated with marked lymphocytic infiltrate. There were unique cases of a posterior wall rupture with hemopericardium and a case with multiple epicardial inflammatory sessile polyps. A novel possible trigger was suggested by a positive serologic test for leptospirosis in one case. The clinical features including age, gender, presenting symptoms, and prognosis resemble those reported in autopsy-based case series from other regions. Conclusions: GCM affects patients in India at approximately the same rate as in Europe and Japan. The clinical and histological features of GCM are similarly severe and suggest a heart-specific autoimmune reaction.