Take Home Message:

Tinea infections are caused by dermatophytes. The term tinea means fungal infection, whereas dermatophyte refers to the fungal organisms that cause tinea. Dermatophytes include three genera: Trichophyton, Microsporum, and Epidermophyton.  

Dermatophytes can be classified into three groups: Trichophyton (which causes infections on skin, hair, and nails), epidermophyton (which causes infections on skin and nails), and Microsporum (which causes infections on skin and hair).

Finally, based upon the affected site, these have been classified clinically into tinea capitis (head), tinea faciei (face), tinea barbae (beard), tinea corporis (body), tinea manus (hand), tinea cruris (groin), tinea pedis (foot), and tinea unguium (nail).

The most common infections in prepubertal children are tinea corporis and tinea capitis, whereas adolescents and adults are more likely to develop tinea cruris, tinea pedis, and tinea unguium (onychomycosis).

Direct microscopic examination: Treatment of skin specimen with 10–20% potassium hydroxide (KOH) is a quick tool to provide evidence of dermatophytic infection.

Tinea corporis, tinea cruris, and tinea pedis generally respond to topical agents such as terbinafine cream or butenafine cream, but oral antifungal agents may be indicated for extensive disease, failed topical treatment, immunocompromised patients, or severe moccasin-type tinea pedis.

Tinea Corporis, Tinea Cruris, and Tinea Pedis

Tinea corporis (ringworm) typically presents as a red, annular, scaly, pruritic patch with central clearing and an active border. Lesions may be single or multiple and the size generally ranges from 1 to 5 cm, but larger lesions and confluence of lesions can also occur.

Tinea corporis may be mistaken for many other skin disorders, especially eczema, psoriasis, and seborrheic dermatitis. A potassium hydroxide (KOH) preparation is often helpful when the diagnosis is uncertain based on history and visual inspection.

Tinea cruris (jock itch) most commonly affects adolescent and young adult males, and involves the portion of the upper thigh opposite the scrotum. The scrotum itself is usually spared in tinea cruris, but involved in candidiasis.

A Wood lamp examination may be helpful to distinguish tinea from erythrasma because the causative organism of erythrasma (Corynebacterium minutissimum) exhibits a coral red fluorescence.

Tinea pedis (athlete's foot) typically involves the skin between the toes, but can spread to the sole, sides, and dorsum of the involved foot. The acute form presents with erythema and maceration between the toes, sometimes accompanied by painful vesicles. The more common chronic form is characterized by scaling, peeling, and erythema between the toes; however, it can spread to other areas of the foot. Involvement of the plantar and lateral aspects of the foot with erythema and hyperkeratosis is referred to as the “moccasin pattern” of tinea pedis.