Histoplasma capsulatum in peripheral blood smear
- 1Southern Illinois University School of Medicine, Internal Medicine, 701 N. First Street, Springfield, IL 62704, USA
- 2Pathology Associates of Central Illinois, Ltd, Department of Pathology and Laboratory Medicine, 701 N. First St, Springfield, IL 62781, USA
- Nishith K Singh,
- Published 28 September 2009
A middle aged male with advanced HIV/AIDS (CD3+/CD4+ lymphocyte count =22 per cubic millimetre) presented with a 5 day history of fever, chills and pulmonary infiltrates. Routine laboratory tests showed a normocytic anaemia (haemoglobin 9.8 g/dl) and neutrophilia (1.59×109/l) with left shift and toxic changes. The peripheral smear was remarkable for multiple toxic vacuolated neutrophils filled with yeast-like organisms suggestive of Histoplasma capsulatum var capsulatum.
Figure 1 shows a central neutrophil filled with multiple phagocytic vacuoles and a single histoplasma organism in the cytoplasm, whereas figs 2 and 3 show neutrophils with multiple histoplasma organisms. In fulminant disseminated histoplasmosis, the yeast can be recognised as intracellular 3–4 μm narrow based organisms with basophilic cytoplasm retracted from the poorly stained cell wall, giving the false impression of a capsule. Despite systemic antifungal therapy, the patient expired secondary to multiorgan dysfunction. Two weeks later, sputum fungal culture turned positive for H capsulatum var capsulatum. The case illustrates the potential utility of peripheral blood smear in early diagnosis of disseminated fungal infection.
Competing interests: None.