GMS stain, high power:
Small, narrow based, budding, intracellular yeast
DQ stain, medium power (BAL specimen):
Negatively staining vacuoles, suggestive of yeast
DQ stain, high power (CSF specimen):
Small blue dots possible yeast
GMS stain, high power:
Note intracellular location
Narrow based budding
Features
Specimen in which encountered
• Bronchioloalveolar lavage or washing
• Cerebrospinal fluid
• Solid organ FNA
Organism
• Histoplasma capsulatum
Morphologic features
• Predominant form: Yeast
• Size: Very small (1-4 µm)
• Location: Predominantly intracellular (inside macrophages)
• Features:
– Small yeast with narrow based budding
– Smaller than Candida
– Lack pseudohyphae
Notes
• Difficult to see and often missed on DQ and Pap stain
• Must do GMS stain