A bone marrow aspirate from a febrile patient with massive splenomegaly shows intracellular round to oval organisms 2 to 4 micrometers in size within macrophages. Which internal structure, seen on Giemsa stain, definitively identifies these as Leishmania donovani amastigotes?
- A A rod-shaped kinetoplast adjacent to the nucleus ✓
- B A large central vacuole
- C Multiple peripheral cilia
- D A thick chitinous cell wall
Correct answer: A. A rod-shaped kinetoplast adjacent to the nucleus
Explanation
The amastigote (Leishman-Donovan body) contains a nucleus and a paranuclear rod-shaped kinetoplast, and this kinetoplast distinguishes it from Histoplasma capsulatum, its chief mimic inside macrophages. Histoplasma lacks a kinetoplast and stains with GMS rather than being a flagellate protozoan. Cilia and cell walls do not occur in Leishmania at any stage.
Reference: Paniker's Textbook of Medical Parasitology, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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