Answer: Leishmania amastigotes
This case shows the characteristic morphology of amastigotes within a macrophage. The arrow below highlights an amastigote in which the nucleus and kinetoplast can both be seen.
One of the most important teaching points about this case is that the patient acquired infection in Italy - a country that many physicians (especially in the United States) do not realize is endemic for Leishmania infantum. Of note, Leishmania infantum is nearly identical to L. chagasi, a pathogen found in the Americas, and some consider them to be the same organism (in which case L. infantum would have preference).
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