SEBORRHEIC DERMATITIS

Seborrheic dermatitis

Seborrheic dermatitis causes a characteristic rash on the hair-bearing areas of the face. Sometimes it can be controlled with dandruff shampoo.

Seborrheic dermatitis is a papulosquamous disorder patterned on the sebum-rich areas of the scalp, face, and trunk. In addition to sebum, this dermatitis is linked to Malassezia, immunologic abnormalities, and activation of complement. It is commonly aggravated by changes in humidity, changes in seasons, trauma (eg, scratching), or emotional stress. The severity varies from mild dandruff to exfoliative erythroderma. Seborrheic dermatitis may worsen in Parkinson disease and in AIDS.

Seborrheic dermatitis is associated with normal levels of Malassezia but an abnormal immune response. Helper T cells, phytohemagglutinin and concanavalin stimulation, and antibody titers are depressed compared with those of control subjects. The contribution of Malassezia species to seborrheic dermatitis may come from its lipase activity—releasing inflammatory free fatty acids—and from its ability to activate the alternative complement pathway.

The prevalence rate of seborrheic dermatitis is 3-5%, with a worldwide distribution. Dandruff, the mildest form of this dermatitis, is probably far more common and is present in an estimated 15-20% of the population.

Seborrheic dermatitis occurs in persons of all races. Seborrheic dermatitis is slightly worse in males than in females. The usual onset occurs with puberty. It peaks at age 40 years and is less severe, but present, among older people. In infants, it occurs as cradle cap or, uncommonly, as a flexural eruption or erythroderma.

How and When seborrheic dermatitis Occures?

Intermittent, active phases of seborrheic dermatitis manifest with burning, scaling, and itching, alternating with inactive periods. Activity is increased in winter and early spring, with remissions commonly occurring in summer.

Active phases of seborrheic dermatitis may be complicated by secondary infection in the intertriginous areas and on the eyelids.

Candidal overgrowth is common in infantile napkin dermatitis. Such children may have a diaper dermatitis variant of seborrheic dermatitis or psoriasis.

Generalized seborrheic erythroderma is rare. It occurs more often in association with AIDS, congestive heart failure, Parkinson disease, and immune suppression in premature infants.

Physical appearance of seborrheic dermatitis

The scalp appearance of seborrheic dermatitis varies from mild, patchy scaling to widespread, thick, adherent crusts. Plaques are rare. From the scalp, seborrheic dermatitis can spread onto the forehead, the posterior part of the neck, and the postauricular skin, as in psoriasis. Note the images below.

Seborrheic dermatitis affecting the scalp line and the eyebrows with red skin and scaling. Courtesy of Wilford Hall Medical Center Dermatology slide files.   Seborrheic dermatitis may affect any hair-bearing area, and the chest is frequently involved. Courtesy of Wilford Hall Medical Center Dermatology Teaching slides.
 

African Americans and persons from other darker-skinned races are susceptible to annular seborrheic dermatitis, also called petaloid seborrheic dermatitis or seborrhea petaloides. Sarcoidosis, secondary syphilis, and even discoid lupus may be in the differential in such cases.

Seborrheic dermatitis skin lesions manifest as branny or greasy scaling over red, inflamed skin. Hypopigmentation is seen in blacks. Infectious eczematoid dermatitis, with oozing and crusting, suggests secondary infection. A seborrheic blepharitis may occur independently.

Distribution follows the oily and hair-bearing areas of the head and the neck, such as the scalp, the forehead, the eyebrows, the lash line, the nasolabial folds, the beard, and the postauricular skin. An extension to submental skin can occur. Presternal or interscapular involvement is more common than nonscaling intertrigo of the umbilicus, axillae, inframammary and inguinal folds, perineum, or anogenital crease, which also may be present.

Two distinct truncal patterns of seborrheic dermatitis can occasionally occur. An annular or geographic petaloid scaling is the most common. A rare pityriasiform variety can be seen on the trunk and the neck, with peripheral scaling around ovoid patches, mimicking pityriasis rosea. Note the image below.

Causes of Seborrheic Dermatitis

Malassezia organisms are probably not the cause but are a cofactor linked to a T-cell depression, increased sebum levels, and an activation of the alternative complement pathway. Persons prone to this dermatitis also may have a skin-barrier dysfunction.

Because seborrheic dermatitis is uncommon in preadolescent children, and tinea capitis is uncommon after adolescence, dandruff in a child is more likely to represent a fungal infection. A fungal culture should be completed for confirmation.

Various medications may flare or induce seborrheic dermatitis. These medications include auranofin, aurothioglucose, buspirone, chlorpromazine, cimetidine, ethionamide, gold, griseofulvin, haloperidol, interferon alfa, lithium, methoxsalen, methyldopa, phenothiazines, psoralens, stanozolol, thiothixene, and trioxsalen.

Differential Diagnoses for Seborrheic Dermatitis

  • Asteatotic Eczema
  • Atopic Dermatitis
  • Candidiasis, Cutaneous
  • Contact Dermatitis, Allergic
  • Contact Dermatitis, Irritant
  • Dermatologic Manifestations of Gastrointestinal Disease
  • Dermatomyositis
  • Drug Eruptions
  • Drug-Induced Photosensitivity
  • Erythrasma
  • Extramammary Paget Disease
  • Glucagonoma Syndrome
  • Impetigo
  • Intertrigo
  • Lichen Simplex Chronicus
  • Lupus Erythematosus, Acute
  • Nummular Dermatitis
  • Pemphigus Erythematosus
  • Pemphigus Foliaceus
  • Perioral Dermatitis
  • Pityriasis Rosea
  • Rosacea
  • Tinea Capitis
  • Tinea Corporis
  • Tinea Cruris
  • Tinea Versicolor

Other Problems to be Considered to identify Seborrheic ermatitis

Xerotic eczema Chronic granulomatous disease Exfoliative erythroderma Facial chapping Infectious eczematoid dermatitis Letterer-Siwe disease Scaling drug eruptions Sebopsoriasis Staphylococcal blepharitis Tinea amiantacea Tinea versicolor Vitamin B and/or zinc deficiency Laboratory Studies of Seborrheic Dermatitis.

A clinical diagnosis of seborrheic dermatitis is usually made based on a history of waxing and waning severity and by the distribution of involvement upon examination.

Procedures

A skin biopsy may be needed in persons with exfoliative erythroderma, and a fungal culture can be used to rule out tinea capitis.

Histologic Findings

Dermatopathologic findings of seborrheic dermatitis are nonspecific. Hyperkeratosis, acanthosis, accentuated rete ridges, focal spongiosis, and parakeratosis are characteristic. Psoriasis is distinguished by regular acanthosis, thinned rete ridges, exocytosis, parakeratosis, and an absence of spongiosis. Neutrophils may be seen in both diseases.

Treatment for Seborrheic Dermatitis

Medical Care

Early treatment of flares is encouraged. Behavior modification techniques in reducing excoriations are especially helpful with scalp involvement.

Topical corticosteroids may hasten recurrences, may foster dependence because of a rebound effect, and are discouraged except for short-term use. Skin involvement responds to ketoconazole, naftifine, or ciclopirox creams and gels. Alternatives include calcineurin inhibitors (ie, pimecrolimus, tacrolimus), sulfur or sulfonamide combinations, or propylene glycol. Class IV or lower corticosteroid creams, lotions, or solutions can be used for acute flares. Systemic ketoconazole or fluconazole may help if seborrheic dermatitis is severe or unresponsive. Combination therapy has been recommended.

Dandruff responds to more frequent shampooing or a longer period of lathering. Use of hair spray or hair pomades should be stopped. Shampoos containing salicylic acid, tar, selenium, sulfur, or zinc are effective and may be used in an alternating schedule. Overnight occlusion of tar, bath oil, or Baker's P&S solution may help to soften thick scalp plaques. Derma-Smoothe F/S oil is especially helpful when widespread scalp plaques are present. Selenium sulfide (2.5%), ketoconazole, and ciclopirox shampoos may help by reducing Malassezia yeast scalp reservoirs. Shampoos may be used on truncal lesions or in beards but may cause inflammation in the intertriginous or facial areas.

Siadat et al reported that 1% metronidazole gel is effective for seborrheic dermatitis of the face. Some suggest using a nonsteroidal cream.

Seborrheic blepharitis may respond to gentle cleaning of eyelashes with baby shampoo and cotton applicators. The use of ketoconazole cream in this anatomical region is controversial.

A severe, explosive onset of seborrheic dermatitis may be a marker for HIV infection, regardless of age. It may appear as a butterfly rash, similar to the acute facial eruption associated with systemic lupus erythematosus. The dermatitis appears early in persons with AIDS, affects 25-50% of persons with AIDS, and has greater involvement and greater activity in those with diminished T-cell function. The dermatitis may be treated with topical preparations, but if severe, treatment with 400 mg of oral ketoconazole daily for 2 weeks may be necessary.

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