Common Skin Diseases

I. Alopecia Areata

A. Alopecia areata is characterized by asymptomatic, noninflammatory, non-scarring areas of complete hair loss, most commonly involving the scalp, but the disorder may involve any area of hair-bearing skin.

B. It is probably caused by auto-antibodies to hair follicles. Emotional stress is sometimes a precipitating factor. The younger the patient and the more widespread the disease, and the poorer the prognosis.

C. Regrowth of hair after the first attack takes place in 6 months in 30% of cases, with 50% regrowing within 1 year, and 80% regrowing within 5 years. Ten to 30% of patients will not regrow hair; 5% progress to total hair loss.

D. Lesions are well defined, single or multiple, round or oval areas of total hair loss. In active lesions, "exclamation point" hairs (loose hairs 3-10 mm in size with a tapered, less pigmented proximal shaft) are seen at the margins.

E. Differential Diagnosis: Tinea capitis, trichotillomania, secondary syphilis, and lupus erythematosus.

F. A VDRL or RPR test for syphilis should always be obtained. A CBC, SMAC, sedimentary rate, thyroid function tests, antinuclear antibody should be done to screen for pernicious anemia, chronic active hepatitis, thyroid disease, lupus erythematosus, and Addison's disease.

G. Therapy. Topical steroids, intralesional steroids, and topical minoxidil may be somewhat effective. Hair regrowth will usually occur in 1 year without therapy.

II. Scabies

A. Scabies is characterized by an extremely pruritic eruption usually accentuated in the groin, axillae, navel, breasts, and finger webs, with sparing the head.

B. Scabies is spread by skin to skin contact. The diagnosis is established by finding the mite, ova, or feces in scrapings of the skin, usually of the finger webs or genitalia.

C. Treatment of choice for nonpregnant adults and children is gamma benzenehexachloride (Kwell), applied for 8-12 hours, then washed off. CNS toxicity has been reported in infants in whom it was used too frequently.

D. Elimite, a 5% permethrin cream, is more effective but more expensive than lindane (Kwell).

E. Treatment should be given to all members of an infected household simultaneously. Clothing and sheets must be washed on the day of treatment. Treatment failures usually result from incomplete treatment or failure to treat all members of the household simultaneously.

III. Acne Rosacea

A. This condition commonly presents in fair-skinned individuals and is characterized by papules, erythema, and telangiectasias.

B. Initial treatment consists of doxycycline or tetracycline. Once there has been some clearing, topical metronidazole gel (Metro-gel) can prevent remission. Sunblock should be used because sunlight can exacerbate acne rosacea.

IV. Seborrheic Dermatitis

A. Seborrheic dermatitis is often called cradle cap, dandruff, or seborrhea. It has a high prevalence in infancy, and then is not common until after puberty. Predilection is for the face, retroauricular region, and upper trunk.

B. Clinical Findings

1. Infants present with adherent, waxy, scaly lesions on the scalp vertex also known as "cradle cap."

2. In adults, the eruption is bilaterally symmetrical, affecting the scalp with patchy or diffuse, dull, yellow-like erythema, and waxy yellow, greasy scaling on the forehead, retroauricular region, auditory meatus, eyebrows, cheeks, and nasolabial folds.

3. Trunk areas affected include the presternal, interscapular regions, the umbilicus, intertriginous surfaces of the axilla, inframammary regions, groin, and anogenital crease.

4. Pruritus is mild, and bacterial infection is indicated by vesiculation and oozing.

C. Treatment

1. Scalp: Selenium sulfide or tar shampoos are useful. Sulfur and salicylic acid lotions can be used as keratolytics; topical corticosteroid lotions are used for difficult lesions.

2. Face, neck, and intertriginous regions: Hydrocortisone 1 or 2 ½%.

3. Trunk: Fluorinated steroids can be used if severe lesions are present.

V. Drug Eruptions

A. Drug eruptions may be type I, type II, type III, or type IV immunologic reactions.

B. Cutaneous drug reactions may start within 7 days of initiation of the drug or within 4-7 days after the offending drug has been stopped.

C. The cutaneous lesions usually become more severe and widespread over the following several days to 1 week and then clear over the next 7-14 days.

D. Lesions most often start first and clear first from the head and upper extremities to the trunk and lower legs. Palms, soles, and mucous membranes may be involved.

E. Most drug reactions appear as the typical maculopapular drug reaction. Tetracycline is associated with a fixed drug eruption; thiazide diuretics have a tendency for photosensitivity eruptions.

F. Treatment of Drug Eruptions

1. Oral antihistamines are very useful. Diphenhydramine (Benadryl), 25-50 mg q4-6h.

2. Soothing, tepid water baths in Aveeno or corn starch or cool compresses are useful.

3. Severe Signs and Symptoms. A 2-week course of systemic steroids (prednisone starting at 60 mg per day and then tapering) will usually stop the symptoms and prevent further progression of the eruption within about 48 hours of the onset of therapy.

G. Erythema Multiforme

1. Erythema multiforme presents as dull red macules or papules on the back of hands, palms, wrists, feet, elbows and knees. The periphery isred and the center becomes blue or darker red, hence the characteristic target or iris lesion.

2. It is most commonly a drug reaction most commonly caused by sulfa medications or phenytoin (Dilantin). It is also seen as a reaction to HSV infections, mycoplasma, and Hepatitis B.

3. Erythema multiforme major or Stevens Johnson syndrome is diagnosed when mucous membrane or eye involvement is present.

4. Prednisone 30-60 mg/day is often given with a 2-4 week taper.

5. For HSV-driven erythema multiforme, acyclovir may be helpful, particularly when given prophylactically in cases of recurrent erythema multiforme secondary to HSV.

6. Ophthalmologic consultation is obtained for ocular involvement.

VI. Nail Infections

A. Perionychias

1. Chronic infections around the edge of the nail, paronychias, are caused almost universally to Candida albicans.

2. Acute perionychia presents as tender, red, swollen areas of the nail fold, but not the nail itself. Pus may be seen through the nail plate or at the paronychial fold. The most common causative bacteria are staphylococci, beta-hemolytic streptococci, and gram-negative enteric bacteria.

3. Predisposing factors to perionychia include minor trauma and splinters under the nail. Moisture predispose to Candida.

4. Diagnosis of Paronychial Lesions. Chronic lesions are usually caused by Candida and may be diagnosed by KOH prep or by fungal culture. Acute lesions are usually bacterial and may be cultured for bacteria.

5. Treatment of Chronic Candida Paronychia

a. Stop all wet work and apply clotrimazole (Lotrimin) 1% solution or thymol 2-4% in chloroform tid.

b. Resistant cases can be treated with a 3-6 week oral course:

(1) Fluconazole (Diflucan), 100 mg PO daily

(2) Itraconazole (Sporanox) 200-400 mg PO daily.

6. Treatment of Acute Bacterial Paronychia

a. Oral Antibiotics

(1) Dicloxacillin 500 mg PO qid.

(2) Cephalexin (Keflex) 500 mg PO qid.

(3) Cefadroxil (Duricef) 500 mg PO bid.

(4) Erythromycin 500 mg PO qid.

b. If redness and swelling do not resolve, and a pocket of pus remains, drainage is indicated.

VII. Tinea Versicolor (Pityriasis Versicolor)

A. Tinea versicolor most commonly presents as small perifollicular, scaly, hypopigmented or hyperpigmented patches on the upper trunk in young adults. The perifollicular patches expand over time and become confluent. These broad, confluent, scaling patches mimic tinea corporis caused by dermatophyte fungi.

B. A negative fungal culture argues against the diagnosis of dermatophyte fungal infection but does not exclude tinea versicolor.

C. In tinea versicolor, fungus does not grow in standard fungal culture media (eg, Sabouraud's dextrose), but KOH examination shows the abundant "spaghetti and meatballs" pattern of short hyphae and round spores. Pityrosporon ovale is part of the normal flora of skin in amounts that are not detectable on KOH examination. It is a yeast infection, and it is not a dermatophyte infection.

D. Effective topical treatment consists of selenium sulfide 2.5% lotion (Exsel, Selsun) applied overnight once a week for 3 weeks. The lotion must cover every inch of the body from the chin to the waist. Topical antifungal creams are more expensive when used repetitively over large areas, as required in tinea versicolor.

1. Miconazole Nitrate (Micatin); apply to affected areas bid; cream: 2% [15, 30 gm].

2. Clotrimazole (Lotrimin), apply to affected area bid for up to 4 wk; cream:1% [15, 30, 45, 90 gm], lotion: 1% [30 mL]

3. Ketoconazole (Nizoral) apply to affected area(s) qd-bid; cream: 2% [15, 30, 60 gm].

E. Effective systemic treatment consists of fluconazole (Diflucan), 400 mg, or ketoconazole (Nizoral), 400 mg, given as a single dose. Fluconazole and ketoconazole are excreted in sweat, where they are present at 20 times their serum levels. Therefore, patients should be instructed to exercise to induce sweating 1 hour after taking the tablets.

F. Relapses are very common. Prophylactic therapy, once weekly to monthly, with topical or oral agents should be encouraged if relapses occur.

VIII. Pityriasis Rosea

A. Pityriasis rosea is an acute inflammatory dermatitis characterized by self-limited lesions distributed on the trunk and extremities. A viral cause is hypothesized. It is most common between the ages of 10 and 35.

B. Clinical Manifestations

1. The initial lesion, called the "herald patch", can appear anywhere on the body, and is 2-6 cm in size, and begins a few days to several weeks before the generalized eruption. The hands, face, and feet are usually spared.

2. The lesions are oval, and the long axes follow the lines of cleavage. Lesions are 2 cm or less, pink, tan, or light brown. The borders of the lesions have a loose rim of scales, peeling peripherally, called the "collarette."

3. Pruritus is usually minimal. Fever and malaise occasionally occur.

C. Differential Diagnosis. Secondary syphilis (always check VDRL for atypical rashes), drug eruptions, viral exanthems, acute papular psoriasis, tinea corporis.

D. Treatment

1. Topical antipruritic emollients (Caladryl) relieve itching. Ultraviolet therapy may be used within the first week.

2. The disease usually resolves in 2-14 weeks and recurrences areunusual. §