[Fever and Pancytopenia - not Always a Case for Oncology].

Introduction: The article describes the case of a 68-year-old patient who was admitted to a clinic after returning from southern Italy with fever, night sweats, and pancytopenia. After extensive diagnostic investigations that ruled out bacterial, viral, and parasitic infections as well as other diseases, visceral leishmaniasis (VL) were eventually diagnosed. This diagnosis was confirmed by the detection of Leishmania sp. in the bone marrow and positive serological tests. Additionally, the patient showed signs of macrophage activation syndrome (MAS), a severe inflammatory reaction that often occurs as a complication of infections or rheumatological diseases. The treatment included liposomal amphotericin B for leishmaniasis as well as steroids and etoposide for the treatment of MAS. The patient recovered after treatment and showed an improvement in general condition during follow-up examinations. The article emphasizes the challenge of correctly diagnosing VL and MAS, especially in combination, particularly in patients outside endemic areas. Rapid diagnosis is crucial, as delays can worsen the prognosis in these severe diseases.