Answer to Image of the Month April 2015
Submitted by Rajalakshmi T
Fungal spores (cryptococcus) on a H&E stained section examined under a fluorescence microscope. The phenomenon is fungal autofluorescence.
The diagnosis of fungal infections can be challenging to a histopathologist, with the fungal elements being scanty or elusive. In such a situation, fungal autofluorescence is helpful. In H&E sections examined under a fluorescence microscope, fungal spores and hyphae show a bright green or green-yellow fluorescence. However, one needs to be aware of other structures like collagen fibrils, bone, and elastic fibres that are also fluorescent, but they are generally yellow in colour. Although not definitive, this is a quick and simple technique for screening multiple sections and selecting slides for performing special stains such as periodic acid-Schiff (PAS) and Gomori methenamine silver (GMS) for confirmation.