Pap stain, low power:
Numerous, negatively stained, thin walled, variably sized spherules
Background shows necrosis
Pap stain, high power:
Fractured/broken Ping-Pong-ball-shaped spherule
Pap stain, high power:
Fractured/broken (Ping-Pong ball) spherule
Note the debris in background
Pap stain, high power:
Fractured spherule releasing numerous endospores
Pap stain, high power:
Extracellular, intact, mature (sporulating) spherule with numerous endospores
GMS stain, low power:
Note variability in size with numerous intact and flattened, large spherules
Scattered small endospores
GMS stain, high power:
Thin-walled mature spherule with numerous endospores
GMS stain, high power:
Variably sized, large, immature spherules, both intact and fractured forms
Note small, scattered uniformly sized endospores in background
Features
• Bronchioloalveolar lavage or washing
• Cerebrospinal fluid
• Lung FNA
Coccidiodes immitis
• Predominant form: Yeast
• Size: Variable sizes - Large spherules (8-10x size of lymphocyte) and small endospores (1/8th to 1/4th of lymphocyte size)
• Location: Predominantly extracellular
• Features of spherules:
– Thin walls
– May have endospores (sporulating, mature) or may not have endospores (immature)
– Often fractured (flattened Ping-Pong ball appearance)
• Features of endospores:
– Non-budding
– Small, round and uniform sized
• Usually necrotic and may have granulomas