A simple method for detecting subcutaneous phaeohyphomycosis with light-colored fungi. A study of eight cases.

Eight cases of subcutaneous phaeohyphomycosis are presented. A lack or scarcity of fungal pigmentation was seen in six of these cases. The simple act of lowering the microscope condenser makes these uncolored fungi easily visible. The thick hyaline capsule becomes refringent, presenting single oval or round cells and septated hyphae, which can be short or elongated, branched or unbranched, and irregularly swollen. The dematiacious character of the fungi is confirmed by using the Fontana-Masson stain. The fungi are not visible under polarized light. Our studies point to the probability of subcutaneous phaeohyphomycosis being a widespread tropical disease in Brazil. However, it is rarely diagnosed because of the common practice of fixing tissue specimens without prior culturing and the difficulties of detecting the fungal forms using customary microscopic procedures, especially when the fungi have a lack of pigment and are hard to detect by hematoxylin and eosin stain.