Tinea capitis is a type of fungal infection (dermatophytosis) of the scalp and hair. Ectothrix and endothrix are two important varieties of Tinea capitis infection. In ectothrix, the fungal hyphae and spores (arthroconidia) cover the outside of the hair. These can be identified by Woods lamp examination (using long wave ultraviolet light). The area affected by ectothrix will fluoresce. Conversely, endothrix exhibits invasion of the hair shaft; this area becomes filled with fungal hyphae and chains of arthroconidia. Infections with dermatophytes such as Trichophyton tonsurans, T. violaceum and T. soudanense will result in endothrix type of invasion. Endothrix infections do not show fluorescence when examined with Woods lamp. Potassium hydroxide (10%) preparation of the hair shaft is usually done for identification of dermatophytic infections of the skin and hair. To identify cases of endothrix specificially, chains of arthroconidia are observed filling the inside of hair shaft, as shown in this image.
The affected hair is collected by clipping and plucking. The hair clip is mounted on a glass slide and 10% potassium hydroxide is added and a cover slip applied. After about 1 hour, the specimen is examined under 100x and then at 400x magnification. The view from the binocular microscope was photographed using the Nikon digital camera (5 mega pixel).