Infectious Disease Online
Cutaneous Infections and Infestations:
Mycoses and Algal Infections
Fungi are an important cause of dermatological disease.
The PAS stain (Periodic Acid-Schiff) , sometimes combined with diastase digestion, is most frequestly used.
It stains the cell walls of fungi a purple colour of varying intensity.
The silver methenamine stain, usually Grocott’s modification, is a reliable method of detecting fungi: It stains them black against a green background.
It is more reliable than the PAS (Periodic Acid-Schiff) stain for detecting degenerate fungal elements and the rare animal pathogens among the aquatic fungi, although it may be less reliable with zygomycetes.
It is usually doubly refractile under polarized light.
Calcoflour white can be used to stain frozen or paraffin sections as well as tissue smears.
The sections must be viewed with a fluorescence microscope.
Certain fungi are even autoflourescent when a section stained with hematoxylin and eosin is exposed to ultraviolet light.
Polymerase chain reaction (PCR)-based techniques are now being used to identify specific species of fungi, including dermatophytes.
Superficial filamentous infections:
Infection by dematiaceous fungi:
Mycetoma and morphologically similar conditions:
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