Clinical Scenario
A 10-year-old boy presents with high-grade fever for 2 months despite several courses of antimalarial and antibacterial therapy. He is febrile (41°C), markedly pale, and has massive splenomegaly and hepatomegaly without jaundice, rash, or lymphadenopathy. Laboratory investigations reveal Hb 5.2 g/dL, TLC 2,250/mm³, lymphocyte count 750/mm³, and platelet count 55,000/mm³. Peripheral smear shows normocytic normochromic anemia. Malaria smear, blood and urine cultures, Widal test, and Brucella serology are negative.
Which of the following is the most appropriate investigation to provide parasitological confirmation of the diagnosis?
A. Bone marrow aspiration with examination for Leishmania amastigotes
B. Blood culture for Salmonella Typhi
C. Lymph-node biopsy with immunohistochemistry
D. Splenic aspiration under ultrasound guidance
E. Tuberculin skin testing
Correct answer & Explanation:
Correct Answer: A. Bone marrow aspiration with examination for Leishmania amastigotes
Discussion: Visceral Lashmaniasis
This child has a classic presentation of visceral leishmaniasis (VL; kala-azar), characterized by prolonged fever, massive splenomegaly with hepatomegaly, anemia, leukopenia, and thrombocytopenia. VL involves the reticuloendothelial system, particularly the spleen, liver, and bone marrow.
Parasitological confirmation can be obtained by demonstrating intracellular Leishmania amastigotes (Leishman-Donovan bodies) in tissue specimens. Bone marrow is an appropriate diagnostic specimen and is substantially safer than splenic aspiration.
Although splenic aspiration generally has higher diagnostic sensitivity, it carries a risk of potentially life-threatening hemorrhage, even when performed under radiological guidance. In this child, the platelet count is only 55,000/mm³, making bone marrow aspiration the more appropriate and safer choice.
Why the other options are incorrect
- B. Blood culture for Salmonella Typhi — The prolonged fever may initially suggest enteric fever, but the massive hepatosplenomegaly with pancytopenia and negative cultures makes this diagnosis unlikely.
- C. Lymph-node biopsy — Lymph-node tissue can occasionally contain Leishmania, but this child has no lymphadenopathy and bone marrow is a more appropriate specimen.
- D. Splenic aspiration — Splenic aspirate has high diagnostic sensitivity, but the procedure carries a significant hemorrhage risk. In this thrombocytopenic child, bone marrow aspiration is safer.
- E. Tuberculin skin testing — This does not establish the diagnosis of VL and would not explain the characteristic clinical picture.
Postgraduate Pearl
rK39 is a useful rapid diagnostic test for VL, but it detects anti-Leishmania antibodies rather than the parasite itself. Antibodies can persist for years after successful treatment, so rK39 cannot reliably distinguish active disease from past infection or be used as a test of cure. Its diagnostic performance also varies geographically and with host factors.
Therefore, when parasitological confirmation is required, demonstration of Leishmania amastigotes in an appropriate tissue specimen provides direct evidence of infection.
Exam Pearl
VL + pancytopenia + massive splenomegaly → think bone marrow involvement.
If parasitological confirmation is required, bone marrow aspiration is safer than splenic aspiration.
References
- Aronson N, Herwaldt BL, Libman M, Pearson R, Lopez-Velez R, Weina P, et al. Diagnosis and treatment of leishmaniasis: clinical practice guidelines by the Infectious Diseases Society of America (IDSA) and the American Society of Tropical Medicine and Hygiene (ASTMH). Clin Infect Dis. 2016;63(12):e202-e264.
- Centers for Disease Control and Prevention. Clinical testing and diagnosis for leishmaniasis [Internet]. Atlanta: CDC; 2024 [cited 2026 Sep 21].
- World Health Organization. Leishmaniasis: diagnosis, detection and surveillance [Internet]. Geneva: WHO [cited 2026 Sep 21].
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