Seronegative visceral leishmaniasis with bone marrow and hepatic involvement

A 62-year-old man living in Italy presented with a 3-week history of fever, pancytopenia, and hepato-splenomegaly that did not respond to broad-spectrum antibiotics. He was recently diagnosed with diffuse large B-cell lymphoma, received 6 cycles of rituximab plus chemotherapy, and achieved a complete response. Blood cultures, polymerase chain reaction (PCR) for Epstein-Barr virus and cytomegalovirus on blood samples, and serologies for Borrelia, Coxiella, Brucella, Bartonella, and Leishmania were negative. No skin lesions or travel history were reported. Histologic examination of bone marrow (BM) (panel A; hematoxylin and eosin [H&E] stain, original magnification ×400) and liver (panel C; H&E stain, original magnification ×400) revealed intracellular Leishmania amastigotes (black arrows) in macrophages and histiocytes (panel A and panel C insets, original magnification ×1000). Immunostaining for CD1a highlighted a characteristic peripheral reinforcement pattern with unstained nuclei of the amastigotes (panel B: BM, original magnification ×400; inset, original magnification ×1000; panel D: liver, original magnification ×400; inset, original magnification ×1000). Subsequent molecular analysis of liver and BM paraffin-fixed samples failed to identify the pathogen, whereas Leishmania infantum was identified on fresh medullary blood by PCR.

Visceral leishmaniasis is a life-threatening condition that requires a prompt diagnosis. Severe hypogammaglobulinemia as a result of lymphoma-associated immunosuppression and rituximab immunotherapy can make serologic status unreliable, as in our case. Therefore, accurate BM sample examination is mandatory and has to be confirmed by molecular analysis.