INFORMACION SOBRE PARTES RELACIONADAS

Superficial fungal infections can be divided into dermatophytic infections, tinea versicolor, and cutaneous candidiasis. Up to 20% of the US population is infected with dermatophytes.

I. Tinea pedis

A. Tinea pedis is the most common dermatophytosis

and may affect up to 70% of adults. Also referred to as athlete's foot, it involves the plantar surface and interdigital spaces of the foot.

B. Trichophyton rubrum accounts for most

dermatophytic foot infections. The three most com- mon clinical forms of tinea pedis are interdigital, moccasin type, and vesiculobullous. Interdigital infection often presents as white, macerated skin between the fourth and fifth toes, but it may appear in any web space.

C. Moccasin-type, or hyperkeratotic, tinea pedis usually

presents as silvery white scales on a red, thickened base on the sole, heel, and sides of the foot. Occa- sionally, a single hand may also be involved. Onychomycosis often is present. Vesiculobullous tinea pedis usually presents as vesicles or pustules on the sole. With each flare of infection, the sole becomes thicker, and maceration, itching, or sec- ondary infection can develop.

D. Most cases of tinea pedis respond to topical agents,

such as econazole (Spectazole), ketoconazole (Nizoral), and terbinafine (Lamisil). Recurrence is common.

II. Tinea corporis

A. Tinea corporis is dermatophytosis of the skin of the

trunk and extremities. Commonly referred to as ringworm, this infection consists of a round, scaly patch that has a prominent, enlarging border and a clear central portion. The prominent edge often contains pustules or follicular papules, and multiple lesions can be present. A deep form of tinea corporis known as Majocchi's granuloma can de- velop. It typically develops after inappropriate topical corticosteroid therapy.

B. Conditions that may appear similar to the infection

include nummular eczema, plaque psoriasis, contact dermatitis, granuloma annulare, and erythema nodosum. Tinea corporis usually responds to topical therapy.

III. Tinea cruris

A. Tinea cruris is dermatophytosis of the proximal

medial thigh and buttock. Also known as jock itch, it is more common in the summer and in persons who wear tight-fitting clothing. Tinea cruris is found primarily in young men.

B. The lesion on the leading edge of the thigh is promi-

nent, with follicular papules and pustules. A ringed lesion typically extends from the crural fold over the adjacent upper inner thigh.

C. Differential diagnosis includes chafing, which often

has sharp demarcation from the normal skin and no scaling in the center of the lesion. Candidiasis can be differentiated from tinea cruris by its irregular border with satellite lesions and scrotal involvement. Tinea cruris often responds to topical therapy.

A. Tinea versicolor is common, in young and mid-

dle-aged adults. The condition is caused by the lipophilic yeasts, Pityrosporum orbiculare and Pityrosporum ovale. P orbiculare is known as Malassezia furfur. Tinea versicolor is also referred to as pityriasis versicolor.

B. Tinea versicolor is typically found on the upper trunk,

neck, and arms. The characteristic finding is skin depigmentation, but lesions can range from red to hypopigmented to hyperpigmented.

C. Tinea versicolor usually does not clear spontane-

ously and may persist for many years. “Spotty body” often presents in adolescence and is associated with itching. Tinea versicolor has a high rate of recurrence, and periodic retreatment may be needed.

D. Differential diagnosis includes vitiligo, tinea corporis,

pityriasis rosea, pityriasis alba, and secondary syphilis.

E. Tinea versicolor responds to topical therapies, such

as terbinafine, econazole, ketoconazole, and sele- nium sulfide lotion or shampoo (Exsel, Head & Shoulders, Selsun). Recurrences may be less frequent if a short course of oral itraconazole (Sporanox) or ketoconazole (Nizoral) is instituted.

V. Tinea capitis

A. Tinea capitis is a dermatophytic infection of the head

and scalp, usually found in infants, children, and young adolescents. Most infections occur in pre- school-aged children in African-American or His- panic populations. Infection can be spread from child to child or from animals to humans.

B. As the inflammatory response to infection increases,

inflammatory alopecia may develop. Breakage of hairs at the roots may result in “black-dot” alopecia. Scaling that resembles seborrheic dermatitis may occur on the scalp. Nodular, boggy swellings known as kerions may develop.

C. Tinea capitis should be considered in any

prepubertal child over the age of 6 months who has scalp scaling. Cervical lymphadenopathy is common in symptomatic children. Fungal culture usually can differentiate tinea capitis from other conditions. Differential diagnosis of tinea capitis includes seborrheic dermatitis, dandruff, scalp psoriasis, atopic dermatitis, bacterial furunculosis, trichotillomania, and alopecia areata.

D. Treatment requires an oral agent, such as

griseofulvin. Other oral antifungal agents have been used successfully. Ketoconazole cream and sham- poo can be added as adjunctive therapy.

VI. Tinea faciei

A. Tinea faciei is a dermatophytosis of the nonbearded

areas of the face. The condition may present as itchy, red skin without a discernible border, or it may have a raised border.

B. Differential diagnosis of tinea faciei includes discoid

lupus erythematosus, lymphocytic infiltration, seborrheic dermatitis, rosacea, and contact dermati- tis. The infection often responds to topical therapy.

VII. Tinea manuum

A. Tinea manuum is an unusual dermatophytic infec-

tion of the interdigital and palmar surfaces. It may coexist with other fungal infections, such as tinea pedis. The palmar surface often has diffuse areas of dry, hyperkeratotic skin. Differential diagnosis should include pompholyx, eczema, secondary syphilis, and callus formation.

B. The condition often responds to topical therapy. VIII. Cutaneous candidiasis

A. Cutaneous candidiasis is caused by C albicans.

Other candidiasis infections include angular cheilitis (perlèche), erosio interdigitalis blastomycetica, candidal intertrigo, balanitis, vaginitis, and paronychia. Involvement of the skinfolds is most common, but any area of the skin with increased moisture is susceptible.

B. Wearing of occlusive clothing, obesity or disorders

affecting the immune system (eg, diabetes, AIDS) may increase susceptibility to candidal infection.

C. Candidal skin infection often presents with ery-

thema, cracking, or maceration. When maceration develops in the web spaces of the fingers, the skin can become soft and white. Candidal skin infection is characterized by irregular (serrated) edges, tissue erythema, and satellite lesions.

D. In patients with normal immunity, candidiasis is most

often treated with topical therapy. Commonly used topical agents include nystatin (Mycostatin), ketoconazole, miconazole, and clotrimazole. Ther- apy with oral fluconazole (Diflucan) is highly effec- tive.

IX. Topical agents

A. Topical treatment alone may be sufficient for

noninflammatory tinea corporis, tinea cruris, tinea faciei, tinea manuum, and tinea pedis.

B. Imidazoles

1. Ketoconazole (Nizoral) 2% is indicated for treat-

ment of tinea corporis, tinea cruris, and tinea pedis. It also is effective for tinea versicolor,

cutaneous candidiasis, and seborrheic dermatitis.

C. Allylamines are effective in treatment of

dermatophytes and Candida, but they have no antibacterial properties. Terbinafine (Lamisil) 1% is approved for treatment of tinea pedis, tinea cruris, and tinea corporis. Terbinafine seems to be more potent than naftifine (Naftin) in eliminating dermatophytosis.

D. Polyenes are useful in topical treatment of

candidiasis, but they have no efficacy against dermatophytes. Nystatin powder (eg, Pedi-Dri) provides drying as well as antifungal action against candidiasis in intertriginous areas (eg, perineum, under breasts). The efficacy of nystatin is similar to that of clotrimazole.

E. Ciclopirox(Loprox) is effective against cutaneous

candidiasis, tinea versicolor, tinea pedis, and tinea cruris.

X. Systemic agents

A. Systemic therapy is indicated for treatment of tinea

capitis, onychomycoses, and recalcitrant cutaneous mycoses. Systemic therapy often is needed in treatment of moccasin-type tinea pedis.

B. Griseofulvin

1. This agent is active against Trichophyton,

Epidermophyton, and Microsporum species but ineffective against yeasts and nondermatophytes. Griseofulvin is first-line therapy for tinea capitis. A dosage of 15 to 25 mg/kg daily of the liquid microsized formula (Grifulvin V) is recommended.

2. Common side effects are rash, hives, headache,

nausea, vomiting, arthralgia, peripheral neuritis, confusion, insomnia, and memory lapse.

C. Ketoconazole (Nizoral)

1. This agent is effective against dermatophytes,

yeasts, and some systemic mycoses. A dosage of 200 mg once daily for 2 to 4 weeks is often effective for tinea cruris, tinea capitis, and tinea pedis. In addition, oral ketoconazole therapy for 1 week may eradicate tinea versicolor.

2. Use of oral ketoconazole is limited by the poten-

tial for hepatotoxicity. Other potential side effects include nausea, vomiting, abdominal pain, diar- rhea, headache, pruritus, insomnia, leukopenia, hemolytic anemia, decreased libido, and impo- tence.

D. Itraconazole (Sporanox)

1. Itraconazole has the broadest spectrum of activity

of all the oral antifungal agents. It is effective against dermatophytes, Candida, some molds, and P ovale. It is effective in treatment of tinea corporis, tinea cruris, tinea pedis, tinea manuum, and onychomycoses.

2. Possible side effects include diarrhea, headache,

rhinitis, dyspepsia, nausea, dry skin, rash, weak- ness, pruritus, dizziness, hypertension, and loss of libido. Itraconazole has interactions with medi- cations metabolized by cytochrome P-450, such as astemizole (Hismanal), triazolam (Halcion), and midazolam (Versed).

E. Terbinafine (Lamisil)

1. Oral terbinafine has shown efficacy in tinea pedis,

tinea cruris, tinea corporis, and onychomycoses. A dosage of 250 mg daily for 6 weeks for finger- nail onychomycosis and 12 weeks for toenail onychomycosis is highly effective. Terbinafine is not effective for cutaneous candidiasis or tinea versicolor.

2. Common side effects include diarrhea, pruritus,

dyspepsia, rash, taste disturbance, abdominal pain, and toxic effects on the liver.

F. Fluconazole (Diflucan)

1. This agent is beneficial in superficial fungal

infections at a dosage of 50 to 200 mg daily for 1 to 4 weeks. It also has been used for treatment of onychomycoses caused by dermatophytes.

2. Fluconazole has significant drug interactions with

astemizole, oral hypoglycemic agents, coumadin, phenytoin (Dilantin), cyclosporine (Sandimmune), theophylline, and cisapride (Propulsid). Side effects include nausea, headache, rash, vomiting, diarrhea, and hepatotoxicity.

References, see page 282.

Common Skin Diseases