A combined hematoxylin and eosin/methnamine silver stain for the histological diagnosis of fungi in tissue sections

Most histochemical stains available for detection of fungi in tissue sections accentuate the fungi but do not selectively stain surrounding tissue. Therefore, the exact location of organisms in tissue and their relationship to important histological features cannot be ascertained with a routine Grocott methenamine silver stain (GMS). We evaluated the utility of a combined H&E/methenamine silver (H&E/MS) protocol that stains surrounding tissue as well as the fungi and modified it for greater rapidity, ease of performance, and improved clarity. Twenty cases of various mycotic diseases were stained with routine H&E, GMS, and the modified combined H&E/MS stain. Both the combination H&E/MS stain and routine GMS readily demonstrated all types of fungi. However, the surrounding tissue that does not selectively stain with routine GMS was easily visualized using the combination stain, allowing a more comprehensive histopathological assessment on a single section. The histological detail was comparable to routine H&E alone. The modified H&E/MS is quick, relatively inexpensive, and uses reagents routinely stocked by histology laboratories. This stain is a valuable addition to the pathologist's armamentarium for detecting fungi in tissue sections.