A 21-year-old male college student presents with superficial lesions on his trunk. The man recently returned from a summer job working as a counselor in a summer camp for underprivileged kids from inner-city neighborhoods. Many of the kids come from relatively poor families that do not practice good personal hygiene. As a result, many of them have minor skin and scalp problems. The man's duties at the camp included supervision of swimming classes and other outdoor activities. He also served as the resident supervisor in one of the cabins in which the kids slept and showered.

On examination, the man is found to have seven distinctive, roughly circular skin lesions on his body. The lesions range from 2 to 8 cm in diameter and are have well demarked edges. The edges of the lesions are highly inflamed, where there is little or no inflammation in the center of the larger lesions. The borders of the lesions are scaly, slightly raised, and noticeable reddened. The centers of some lesions are hypopigmented. The man indicates that the lesions first developed about three weeks earlier and have been enlarging steadily sine that time. They are quite itchy, but not overtly painful. The lesions appear to be pretty superficial, affectng only the cutaneous layers of the skin. The man's vital signs are normal, and there are no other remarkable physical findings.

Question 8.1: What is your diagnosis?

Expanding annular lesions with inflamed, raised, well demarcated margins are highly suggestive of tinea corporis, more commonly known as ringworm of the body. The term tinea comes from the Latin word for worm and refers to the serpentine lesions that are characteristic of the disease and that appear as though a worm is burrowing at their margin.

Question 8.2: What is the causative agent?

Tinea corporis is caused by various species of dermatophyte fungi, especially those in the genera Trychophyton and Microsporum. Trichophyton rubrum is the most frequently encountered causative agent.

Question 8.3: How is the diagnosis confirmed?

The preliminary diagnosis is made primarily on clinical grounds (i.e., the physical appearance of the lesions and the history of their development). The diagnosis usually can be confirmed by microscopic examination of a small fragment of scale scraped from the edge of a lesion. The scale specimen is treated with KOH and examined (as a wet mount) for the presence of fungal hyphae (branching filaments) with lines of separation appearing at regular intervals (i.e., septate hyphae). Culturing of the scale usually isn't necessary, but this can be done to identify the causative agent if that is of interest to the attending physician.

Test Results:

Septate fungal hyphae are readily observed in the KOH-treated scraping from one of the patient's lesions. The lab cultures a fungus named Trichophyton tonsurans from the scraping sample.

Question 8.4: How typical are the patient's lesions?

The lesions described in this case represent the more or less classical syndrome of tinea corporis. However, tinea lesions actually can vary widely in appearance. They may be scaly, vesicular, or pustular. Inflammation may be minimal or intense. Central healing may or may not take place, but the well demarcated borders are usually present.

Question 8.5: How was the man infected?

Most likely, he acquired the fungus by direct contact with one or more of the children at the summer camp. Some of the children might have had tinea corporis (ringworm of the scalp) which is fairly common among children from families of low socioeconomic status, especially if they do not practice good personal hygiene. Perhaps the man's skin came into direct contact with an infected scalp while helping the children during swimming lessons. Establishment and subsequent growth of the fungus on his skin would have been encouraged by the moist environment.

Question 8.6: How common is this disease?

Tinea (ringworm) infections are extremely common and are probably the most frequently occurring form of fungal disease worldwide. Tinea corporis is most common in warm climates (which favor the growth and survival of the fungi that cause it). It occurs in patients of all ages, and the incidence is the same in males and females.

Question 8.7: Is this disease dangerous?

Tinea infections almost always remain superficial in otherwise healthy persons, even when they are left untreated. When treated correctly, they typically resolve within 3-4 weeks, without leaving any noticeable sequelae.

Question 8.8: How should you treat this case?

Various creams are effective, including those containing miconazole (2% cream applied bid for 2 wk), clotrimazole (1% cream, applied and gently massaged into the affected areas and surrounding areas bid for up to 4 wk), naftifine (1% cream applied qd), or econazole (1% cream, applied qd). Systemic therapy is used only in very severe cases and is usually given for up to 4 wk. The most commonly used agents are ketoconazole (200 mg qd), itraconazole (100-200 mg qd for 2-4 wk), fluconazole (200 mg qd), terbinafine (250 mg qd), and griseofulvin (250-500 mg bid). It is recommended that patients with recurrent or persistent infections be referred to a dermatologist.