Histoplasmosis is caused by Histoplasma capsulatum. It is endemic in North and Central America. Clinical manifestations varies from pulmonary disease to disseminated multi-organ involvement.
Bone marrow aspirate from a patient with disseminated histoplasmosis. Organisms are seen within the macrophage. They are identified by the “capsule”, which is, in reality, an artefact resulting from cytoplasmic shrinkage. 
Bone marrow aspirate from a patient with disseminated histoplasmosis. Organisms are seen within the macrophage. They are identified by the “capsule”, which is, in reality, an artefact resulting from cytoplasmic shrinkage.
Blood Film Features:
- Histoplasma appears as capsulated cytoplasmic inclusions in the neutrophils.
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Bone marrow aspirates from a patient with histoplasmosis. Note the histiocytes with intracellular histoplasma.
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Bone marrow trephine of patient with bone involvement of histoplasmosis. Note the granuloma and histocytes with intracellular fungi.
Bone Marrow Features:
- Histiocytes with numerous intracellular fungal organisms
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