• Skin should be scraped from the margin of the lesion onto folded black paper.
• Hair should be plucked, not cut, from the edge of the lesion.
• Choose hairs that fluoresce under a Wood's lamp or, if none fluoresce, choose broken or scaly ones.
• Nails scrapings are obtained from the nail bed or from infected areas after the outer layers are discarded.

Direct Examination:

• A small sample of the specimen is selected for direct microscopic examination and investigated for the presence of fungal elements.
• The specimen is mounted in a small amount of potassium hydroxide or calcofluor white.
• The KOH slides are gently heated and allowed to clear for 30 to 60 minutes before examining on a light or phase contrast microscope.
• Calcofluor white slides are examined on a fluorescent microscope.
• 

When present in the direct examination dermatophytes appear as hyaline (non-pigmented), septated elements. Hyphae rounding up into arthroconidia are diagnostic of dermatophyte involvement. Without the presence of arthroconidia the elements could also be due to a non-dermatophyte agent of onycomycosis or a small segment of a contaminating organism. When hair is involved the arthroconidia may be found on the periphery of the hair shaft (ectothrix) or within the shaft (endothrix).

Endothrix - within the hair shaft	Ectothrix - arthroconidia on the periphery of the hair shaft

Malassezia furfur infections (tinea versicolor) are diagnosed by the presence of spherical yeast cells with a single bud and a collar and short curved hyphal strands.

Culture

• Nails are scraped or minced into small pieces
• Hair is cut into short segments
• Each specimen is divided between at least two types of culture media
• The use of antibiotics will inhibit the overgrowth of bacteria and incorporation of cycloheximide will prevent the overgrowth of the rapidly growing saprophytic fungi
• The cultures are incubated at 30°C and examined frequently for 4 weeks.