Pap stain, low power:
Broad, ribbon-like hyphae which often show twisting
Note the lack of septae
Pap stain, medium power:
Conglomerate of hyphae which lack septae
Note right angled branching
Pap stain, high power:
NOTE that branching may not seem right angle. Lack of septation is important in such cases
GMS stain, high power:
Note that hyphae are broad and ribbon like
Note that the right angle branching is focal
GMS stain, high power:
Note that hyphae may be fragmented but are always broad and aseptate
Branching may be absent and may not seem right angled
Features
• Sinonasal washings
• Bronchioloalveolar lavage or washing
• Solid organ FNA
• Mucor
• Rhizopus
• Cunninghamella
• Predominant form: Hyphae
• Size: Variable
• Location: Extracellular
• Features:
– Broad, ribbon-like hyphae
– Aseptate
– Right angle branching
• Recommend reporting as: Non-branching, aseptate hyphae; correlate with cultures
• It is medical emergency since these are vasoinvasive
• Goal of cytology is to distinguish aseptate (Zygomycetes) from septate hyphae (Aspergillus)