Overview of Dermatophytoses

Symptoms and signs of dermatophytoses vary by site (skin, hair, nails). Tinea is named according to the part of the body affected (eg, tinea pedis is infection of the feet, tinea cruris is infection of groin/crural folds). Organism virulence and host susceptibility and hypersensitivity determine the severity of presentation.

Most often, there is little or no inflammation; asymptomatic or mildly itching lesions with a scaling, slightly raised border can remit and recur intermittently.

Manifestations of dermatophyte infections typically include:

• Annular, erythematous, scaly plaques with central clearing and an active raised border on glabrous skin (eg, tinea corporis)

• Pruritus, whitish, macerated, and sometimes fissured lesions in intertriginous areas (eg, tinea cruris, some forms of tinea pedis)

• Patchy alopecia with scaling and possible inflammation on the scalp (eg, tinea capitis)

• Distal or lateral nail discoloration, thickening, and onycholysis in onychomycosis, subungual debris

Chronicity and recurrence are frequent for all types of dermatophyte infection.

Occasionally, inflammation is more severe and manifests as sudden vesicular or bullous disease (usually of the foot) or as an inflamed boggy lesion of the scalp (kerion). Chronic or glucocorticoid-modified infectious lesions (also called tinea incognito) may lack classic features.

• Primarily physical examination

• Potassium hydroxide wet mount

The diagnosis of dermatophytoses is based on clinical appearance and site of infection and can be confirmed by skin scrapings and demonstration of hyphae on potassium hydroxide (KOH) wet mount or by culture of plucked hairs. For KOH wet mount for nails, the affected area of the nail plate (nail clippings), not subungual debris, should be pared and tested.

For onychomycosis, the most sensitive test is a periodic acid-Schiff stain of nail clippings.

Identification of specific organisms by culture is unnecessary except for scalp infection (where an animal source may be identified and treated) and nail infection (which may be caused by a nondermatophyte). Culture may also be useful when overlying inflammation and bacterial infection are severe and/or accompanied by alopecia.

The differential diagnosis of dermatophytoses includes:

• Folliculitis decalvans (a rare, scarring alopecia in which a patch of alopecia with pustules enlarges)

• Bacterial pyodermas

• Entities that cause scarring alopecia, such as discoid lupus erythematosus, lichen planopilaris, and pseudopelade

• Dissecting cellulitis

• Inverse psoriasis

• Other intertrigo (eg, those caused by Candida species)

• Erythrasma

• Cutaneous T-cell lymphoma (mycosis fungoides)

• Allergic or irritant contact dermatitis

• Erythema migrans (especially in cases with extensive central clearing)

Features favoring tinea over other diagnoses include the presence of characteristic annular lesions with peripheral scale and central clearing, presence on typical locations (eg, trunk, groin, feet, hands), “two feet-one hand” syndrome (ie, fungal infections on both feet but only one hand), and positive KOH preparation on diagnostic testing.

• Topical or oral antifungals

Topical antifungals are generally adequate for skin infections (see table Options for Treatment of Superficial Fungal Infections). Over-the-counter (OTC) topical terbinafine is fungicidal and allows for shorter treatment duration. Topical econazole or ciclopirox may be better if candidal infection cannot be excluded. Other adequate OTC topical treatments include clotrimazole and miconazole. ). Over-the-counter (OTC) topical terbinafine is fungicidal and allows for shorter treatment duration. Topical econazole or ciclopirox may be better if candidal infection cannot be excluded. Other adequate OTC topical treatments include clotrimazole and miconazole.

Oral antifungals (eg, terbinafine, itraconazole) are used for most nail and scalp infections, resistant skin infections, and patients unwilling or unable to adhere to prolonged topical regimens; doses and duration differ by site of infection. For treatment of fungal nail infections, see Oral antifungals (eg, terbinafine, itraconazole) are used for most nail and scalp infections, resistant skin infections, and patients unwilling or unable to adhere to prolonged topical regimens; doses and duration differ by site of infection. For treatment of fungal nail infections, seeTreatment of Onychomycosis.

For the oral antifungal agents terbinafine and itraconazole, baseline and periodic liver testing is generally advised if treatment extends beyond 4 weeks, as clinically significant hepatic abnormalities are rare but can occur (For the oral antifungal agents terbinafine and itraconazole, baseline and periodic liver testing is generally advised if treatment extends beyond 4 weeks, as clinically significant hepatic abnormalities are rare but can occur (1). Hepatic toxicity is more likely with prolonged therapy and in patients with preexisting liver disease.

Nail lacquers can be a reasonable option for controlling onychomycosis. Complete cure rates are usually low as are side effects; however, nail lacquers can be helpful in improving the appearance of affected nails and reducing nail thickness to make clipping nails more manageable.