Tinea PedisTinea pedis is a dermatophytic infection of the feet, characterized by erythema, scaling, maceration, and/or bulla formation. In most cases of epidermal dermatophytosis, the infection occurs initially on the feet, and, in time, spreads to sites such as the inguinal area (tinea cruris), trunk (tinea corporis), hands (tinea manuum). Tinea pedis often provides breaks in the integrity of the epidermis through which bacteria such as Staphylococcus aureus or group A streptococcus (GAS) can invade, causing localized infection or spreading infections such as cellulitis or lymphangitis. Synonym: Athlete's foot.EpidemiologyAge of OnsetLate childhood or young adult life. Most common, 20 to 50 years.SexMales > females.Predisposing FactorsHot, humid weather; occlusive footwear; excessive sweating.TransmissionWalking barefoot on contaminated floors. Arthrospores can survive in human scales for 12 months.HistoryDurationMonths to years. Often, prior history of tinea pedis, tinea unguium of toenails. May flare if in hot climate.Skin SymptomsAsymptomatic frequently. Pruritus. Pain with secondary bacterial infection.Physical ExaminationSkin LesionsInterdigital TypeTwo patterns: (1) dry scaling (Fig. 23-3); and (2) maceration, peeling, fissuring of toe webs (Fig. 23-4). Hyperhidrosis common. Most common site: between fourth and fifth toes. Infection may spread to adjacent areas of feet.

Moccasin TypeWell-demarcated erythema with minute papules on margin, fine white scaling, and hyperkeratosis (Figs. 23-5 and 23-6) (confined to heels, soles, lateral borders of feet). Distribution: Sole, involving area covered by a ballet slipper. One or both feet may be involved with any pattern; bilateral involvement more common.Inflammatory/Bullous TypeVesicles or bullae filled with clear fluid (Fig. 23-7). Pus usually indicates secondary S. aureus infection or group A streptococcus. After rupturing, erosions with ragged ringlike border. May be associated with "id" reaction (autosensitization or dermatophytid). Distribution: Sole, instep, webspaces.Ulcerative TypeExtension of interdigital tinea pedis onto dorsal and plantar foot. Usually complicated by bacterial infection.