Infiltration of histiocytes and multinucleated giant cells in the myocardium of a patient with multicentric reticulohistiocytosis.

Multicentric reticulohistiocytosis (MRH) is a rare multisystem disease characterized by skin nodules and a destructive polyarthritis. We describe cardiac disease in a 42-year-old African American female with a history of MRH for 29 years and dilated cardiomyopathy for 5 years. During a congestive heart failure flare, the patient was slow to respond to standard treatment. A left/right heart catheterization and endomyocardial biopsy were performed, and the patient was found to have evidence of myocardial MRH infiltration.