A 65-year-old man received a heart transplant because of nonischemic cardiomyopathy 3 years previously. He presented with inguinal lymphadenopathy, which showed reactive follicular hyperplasia and focal paracortical monocytoid B-cell proliferation (panels A-B; original magnification ×40 [A], ×200 [B]; hematoxylin and eosin stain). Remarkably, scattered macrophages within the monocytoid B-cell regions contained abundant microorganisms resembling Leishman-Donovan bodies (panel C; original magnification ×400, ×1000 [inset]; hematoxylin and eosin stain). Upon consultation with the Centers for Disease Control and Prevention (CDC), suspicion for Chagas disease was raised. Additional history revealed that the patient grew up on a farm in Mexico with many animals. Retrospective review of the explanted heart revealed chronic myocarditis but no obvious microorganisms (panel D; original magnification ×100; hematoxylin and eosin stain). The heart and lymph node specimens were sent to the CDC for polymerase chain reaction assays, both of which were positive for Trypanosoma cruzi but negative for Leishmania and Toxoplasma gondii. Fresh serum tested at the CDC was also positive for T cruzi antibody. Subsequently, the patient was managed with benznidazole and remained free of lymphadenopathy or abnormal cardiac function during the 4 years of clinical follow-up after lymph node biopsy.

Chagas disease may spread to countries where it is not endemic with unusual presentations (ie, lymph node involvement in this case). Therefore, examination of lymph nodes may provide additional clues in diagnosing Chagas disease to prevent reactivation after heart transplantation.