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Autofluorescence of fungi: an aid to detection in tissue sections
Abstract:
Many pathogenic fungi have been found to autofluoresce in routine hematoxylin and eosin sections when exposed to ultraviolet light. These fungi include Blastomyces, Cryptococcus, Candida, Aspergillus, Coccidioides, and occasionally, Histoplasma. No autofluorescence was observed with Mucor. Examinations of other inflammatory processes, including those producing a granulomatous response, have not revealed any false-positive results. The advantages of fluorescent microscopy for fungal screening include: (1) no special staining procedures required; (2) no time delay, as involved with special stains; (3) the ability to scan sections at a relatively low power; and (4) the ability to tentatively identify the fungus. Disadvantages may include: (1) lack of a fluorescent microscope, and (2) a possible aging process whereby autofluorescence is lost in older cases.
Insights
Pathogenic fungi like Blastomyces and Candida autofluoresce under ultraviolet light in tissue sections, aiding rapid identification. This method offers advantages over traditional stains for fungal screening in diagnostic pathology.
Area of Science:
- Medical Mycology
- Histopathology
- Microscopy
Background:
- Pathogenic fungi often exhibit autofluorescence when exposed to ultraviolet light in routine tissue sections.
- This phenomenon is observed in common fungal pathogens such as Blastomyces, Cryptococcus, Candida, Aspergillus, and Coccidioides.
- Mucor species do not exhibit autofluorescence, and other inflammatory processes do not yield false positives.
Purpose of the Study:
- To evaluate the utility of autofluorescence microscopy as a rapid screening tool for fungal elements in histopathology.
- To identify which pathogenic fungi demonstrate autofluorescence in hematoxylin and eosin (H&E) stained sections.
- To compare the advantages and disadvantages of autofluorescence microscopy with conventional staining methods for fungal detection.
Main Methods:
- Examination of routine hematoxylin and eosin (H&E) stained tissue sections under ultraviolet (UV) light microscopy.
- Systematic observation for autofluorescence in various fungal infections.
- Comparative analysis with standard fungal stains and other inflammatory conditions.
Main Results:
- Multiple pathogenic fungi, including Blastomyces, Cryptococcus, Candida, Aspergillus, and Coccidioides, demonstrated autofluorescence.
- Histoplasma occasionally showed autofluorescence, while Mucor did not.
- No false-positive autofluorescence was observed in other inflammatory processes, including granulomatous responses.
Conclusions:
- Autofluorescence microscopy provides a rapid, stain-free method for preliminary fungal screening in histopathology.
- The technique allows for low-power scanning and tentative identification of fungi, reducing diagnostic time.
- Limitations include the requirement for a fluorescence microscope and potential loss of signal in older tissue samples.