## Distinguishing Features of Visceral vs Cutaneous Leishmaniasis **Key Point:** The hallmark of kala-azar is dissemination of *Leishmania donovani* to the reticuloendothelial system (liver, spleen, bone marrow, lymph nodes), where amastigotes multiply within macrophages as Leishman–Donovan (LD) bodies. This systemic involvement is pathognomonic for visceral leishmaniasis. ### Comparative Table: Visceral vs Cutaneous Leishmaniasis | Feature | Visceral (Kala-azar) | Cutaneous | | --- | --- | --- | | **Parasite species** | *L. donovani* | *L. tropica*, *L. major*, *L. mexicana* | | **Site of LD bodies** | Macrophages of liver, spleen, bone marrow, lymph nodes | Dermis and epidermis at lesion site | | **Clinical presentation** | Fever, hepatosplenomegaly, pancytopenia, wasting | Ulcerating nodule/plaque at bite site | | **Leishmanin test** | Negative (anergy) | Positive (cell-mediated immunity) | | **Organomegaly** | Massive (up to 10 kg splenomegaly) | Absent | | **Diagnostic site** | Bone marrow, splenic aspirate | Lesion margin biopsy | **High-Yield:** The *negative leishmanin test in kala-azar* reflects immune suppression by the parasite, whereas cutaneous leishmaniasis shows a positive test due to intact cell-mediated immunity. **Clinical Pearl:** LD bodies are found in abundance in visceral leishmaniasis (especially splenic aspirate — 95% sensitivity) but are sparse or absent in cutaneous disease, making this the single best discriminator. ### Why This Matters - Visceral leishmaniasis is a systemic infection with high mortality (>90%) if untreated; cutaneous disease is localized and self-limiting in most cases. - Bone marrow or splenic aspirate showing LD bodies confirms kala-azar diagnosis; their absence in cutaneous lesions is expected. [cite:Park 26e Ch 8]
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