Case #372 – May 2014

A 45-year-old patient originally from Mexico presented with a left groin lymphocele, erythema, swelling in his lower extremities, and fever and chills approximately one month after receiving a heart transplant. An endomycardial biopsy was performed and blood specimens were collected in EDTA and sent to Hematology for work-up. Objects of interest were observed by the attending pathologist on a thin blood film stained with Wright stain. Images were captured and sent to the DPDx Team for diagnostic assistance. Figures A–D show four of the images submitted. What is your diagnosis? Based on what criteria?

Figure A

Figure B

Figure C

Figure D

This was a case of Chagas disease (American trypanosomiasis) caused by Trypanosoma cruzi. Diagnostic morphologic features included:

trypomastigote forms of the parasite with a large posterior kinetoplast and an undulating membrane with an anteriorly-directed flagellum (Figures A–D).
trypomastigotes exhibiting a C-shaped form (Figures A and D).

The patient’s origin in Latin America was also important, as the other human trypanosome species, T. brucei, is endemic to Africa.