Extranodal Rosai-Dorfman disease involving the heart: report of two cases.

Sinus histiocytosis with massive lymphadenopathy (Rosai-Dorfman disease) is a rare disease that typically occurs in lymph nodes. While many body sites have been reported to be involved in extranodal manifestations of the disease, the cardiovascular system has been largely absent in this literature. We report two cases of Rosai-Dorfman disease that involves the heart. Case 1 was a 40-year-old man with chronic myelomonocytic leukemia who was incidentally noted to have Rosai-Dorfman disease on autopsy after succumbing to respiratory failure in the setting of adult respiratory distress syndrome. Case 2 was a 57-year-old woman known to have Rosai-Dorfman disease involving mediastinal lymph nodes and found to have a right atrial mass on workup for atypical chest pain. Both cases showed a similar histologic picture of large, multinucleated histiocytes with immunoreactivity to S100, emperipolesis, and marked plamacytosis. This study expands our knowledge of organs involved in extranodal Rosai-Dorfman disease.