A Case of Kala-azar Diagnosed via PET/CT and Confirmed by Splenectomy

Objective: Visceral leishmaniasis (VL), also known as kala-azar, is an opportunistic infection primarily affecting immunocompromised individuals. It is most commonly caused by Leishmania donovani and L. infantum. We present the case of a 48-year-old male patient with a 4-week history of fever and splenomegaly. Case: On physical examination, the patient had a fever of 39.5°C and a 10 cm splenomegaly. Laboratory tests included serum C-reactive protein (CRP), complete blood count, protein electrophoresis, and other biochemical parameters. FDG PET/CT imaging revealed an increased spleen-to-liver SUVmax ratio and heterogeneous diffuse uptake in the spleen The patient was initially diagnosed with isolated splenic lymphoma and underwent splenectomy on the 13th day of hospitalization. Histopathological and immunohistochemical evaluation of the spleen led to the diagnosis of kala-azar. The patient received appropriate treatment and was subsequently discharged. Conclusion: This case underscores the diagnostic value of FDG-PET/CT in patients presenting with fever of unknown origin and unexplained splenomegaly. In regions where visceral leishmaniasis is endemic or in immunocompromised patients, kala-azar should be considered as a differential diagnosis. FDG-PET/CT not only aids in detecting splenic involvement but also provides insight into disease activity through its functional imaging capabilities, allowing for timely and accurate diagnosis even before significant morphological changes occur. Early identification and intervention are critical for improving outcomes and preventing complications in VL. Therefore, FDG-PET/CT should be recognized as a valuable diagnostic tool in the clinical workup of suspected visceral leishmaniasis.