Alopecia/tinea

Scalp ringworm usually presents with either a single area or multiple areas of alopecia. Unlike alopecia areata the skin looks abnormal and inflamed, although the appearance may vary depending on the causative fungus. In cases of human (anthropophilic) fungi, the inflammation may be minimal unlike animal ringworm where host resistance is high and inflammation may be extensive. The degree of hair loss depends on the amount of damage done by the fungus. Tinea capitis usually responds well to oral griseofulvin or ketoconazole.

Tinea pedis

Known commonly as athlete's foot, tinea pedis is usually acquired in communal changing rooms. As in this case, the toe webs are commonly affected producing peeling, erythema and scaling. The distribution is usually asymmetrical predominantly affecting the spaces between the fourth and fifth toes. However, intertrigo, caused by wearing tight-fitting shoes and sweating, can produce the same appearance. Scraping for mycology will give a definitive diagnosis. This condition is often mistaken for eczema and treated with topical steroids that encourage its spread to the rest of the foot. The treatment of choice is usually topical antifungals, although in some cases oral treatment will be required.

Tinea incognito

With an increase in the availability of OTC steroid creams, treatment without medical advice is becoming increasingly common. Pharmacists are generally knowledgeable and can recognise the difference between eczema and ringworm. However, when mistakes are made and steroid is applied to a fungal infection the result can be a condition called tinea incognito. The steroid not only prevents the condition getting better but also changes the appearance of the lesion making it look more like eczema and so increasing the likelihood that stronger steroids will be applied by GPs. As a simple rule, any skin condition that fails to respond as expected to normal treatments may need to have the diagnosis reconsidered. Skin scrapings can help to detect a fungus, although if in doubt it may be worth simply stopping a steroid and trying an antifungal instead.

Trichophyton rubrum              

Before the Second World War Trichophyton rubrum infection was rare in the UK. Troops returning from the Far East during the War brought the infection with them and it is now thought to be the most common dermatophyte infection. As with other dermatophyte infections, it generally starts on the feet but does not cause a vesicular response so inflammation is often minimal. Affected skin has a dry and powdery appearance with peeling in the creases. Nails are commonly affected and the fungus may spread to the skin of the legs where it can cause Majocchi's granuloma, a nodular annular lesion.

Onychomycosis

Tinea infections affecting the nail beds and nails are very common in adults and are usually associated with tinea pedis. The distal areas of the nail are often affected first with yellowish streaks in the nail plate that gradually extend to include the whole nail.

The nails commonly become thickened and a marked subungual hyperkeratosis occurs which can be painful especially when pressure is applied from shoes. In the case shown here, the cause is almost certainly fungal, but in order to confirm this before treatment nail clippings should be sent for microscopy and culture. Treatment is with an oral antifungal such as terbinafine which usually has to be taken for three months for fingernails and up to six months for toenails.

Pityriasis versicolor

This common condition is the result of an overgrowth of the commensal yeast Pityrosporum orbiculare especially in hot humid conditions. Carboxylic acids released by the organisms inhibit normal pigment production by melanocytes after exposure to sunlight, producing the characteristic patchy hypopigmentation usually seen over the trunk. Fine scaling on the surface of the lesions is common and it is usually more apparent after tanning in the summer. Treatment is with a topical antifungal. The easiest way to do this is by using an antifungal shampoo such as ketoconazole which can be applied directly to the skin then rinsed off. Patients need to be advised that it may take many months for repigmentation to occur.