When evaluating rashes on the feet, the distribution and type of lesions should be noted and the toe clefts and toenails carefully examined. Diagnostic clues, such as psoriatic plaques on the scalp, knees or elbows, or flexural changes of eczema, should also be sought elsewhere on the body. In addition, fungal cultures of skin and/or toenails are often necessary, swabs may be needed and biopsy of the lesions may be required to provide a specific diagnosis.
In considering the distribution of rashes on the feet, it is useful to remember that unilateral rashes are more likely to be fungal than psoriatic or eczematous. The clinician should also be familiar with the significance of the wide spectrum of clinical signs that may be present in patients with feet dermatoses. These include the characteristic erosions of pitted keratolysis, the peeling, maceration and fissuring of fungal infection in the toe clefts or soles, and the dystrophic toenails that suggest psoriasis or fungal infection.