The kinetoplast in the diagnosis of visceral leishmaniasis

Abstract

In visceral leishmaniasis (as in all leishmanial infections), microscopic diagnosis is made by observing the intracellular amastigote form, complete with a kinetoplast, in aspirate smears or biopsied tissue. In the 2 clinically-ill patients described here, intracellular inclusions were demonstrated in a bone marrow aspirate or a colon tissue biopsy. Kinetoplasts associated with the inclusions were not identified in the marrow aspirate smear (although the patient was treated for visceral leishmaniasis), but were identified retrospectively in the colonic tissue (although the patient was treated for histoplasmosis). Both cases illustrate the importance to clinical consultants of microscopically observing (or not) an associated kinetoplast when faced with a tissue aspirate or biopsy specimen showing intracellular inclusions.

Keywords: AIDS, acquired immunodeficiency syndrome; HLH, hemophagocytic lymphohistiocytosis; Hemophagocytic lymphohistiocytosis; Kinetoplast; Leishmania; Visceral leishmaniasis.

Fig. 1

(A-C). Bone marrow aspirate smear from Patient 1 showing macrophages (arrow) in adjacent fields with numerous intracellular inclusions but no identifiable or clearly-associated kinetoplast-like structures. Hematoxylin-eosin stain; original magnification, x1000.

Fig. 2

Colonic biopsy tissue (A) and bone marrow aspirate smear (B) from Patient 2. In (A), arrows indicate two amastigotes with identifiable kinetoplasts. Note adjacent “nest” of forms (arrowhead) possibly resembling a T. cruzi “pseudocyst.” In (B), arrows indicate characteristic Leishmania amastigote morphology in extracellular forms released during smear preparation. Hematoxylin-eosin (A) and Wright-Giemsa (B) stains; original magnification, x1000.

Fig. 3

Characteristic amastigotes with identifiable kinetoplasts (arrows) in liver biopsy tissue (A) and within macrophages in bone marrow smears (B, C). Giemsa (A), and Wright-Giemsa (B, C) stains; original magnification x1000.