We describe two cases of kerion caused by Trichophyton rubrum and Microsporum gypseum. In the histological sections, a PAS stain revealed a small number of hypha-like rods and spore-like round bodies in the dermis of patient 1. Except for some clusters of PAS-positive materials, no definite fungal elements were observed in the dermis of patient 1, whereas a considerable number of hyphae were demonstrated within a hair shaft. Immunofluorescence staining, using fluorescein-labeled T mentagrophytes antiserum, disclosed the presence of fungal antigens, not only within a hair shaft, but also in the inflammatory infiltrate in the dermis of both patients.
Imamura S, Tanaka M, Watanabe S. Use of Immunofluorescence Staining in Kerion. Arch Dermatol. 1975;111(7):906-909. doi:10.1001/archderm.1975.01630190096014