Seborrheic Dermatitis- Clinical Features, Causes, and Treatment

Seborrheic dermatitis is a chronic inflammatory condition of the skin that causes an itchy rash with flaky scales and red skin.

It is a chronic or relapsing type of eczema or dermatitis that mainly affects the sebaceous, gland-rich regions of the scalp, face, and trunk.

It is also called dandruff, seborrhea, seborrheic eczema, or seborrheic psoriasis. In infants, it is known as cradle cap and results in scaly and crusty patches on the scalp or diaper area.

Seborrheic dermatitis is the single most common inflammatory skin disease affecting human beings apart from acne vulgaris.

It has a worldwide distribution affecting around 11% of the world’s population. Dandruff, the mildest form of this dermatitis, is the most common form of the disease. In infants, the prevalence is greater with about 70% of the babies being affected.

It occurs in persons of all ages and ethnicity. However, it is most common in infants and adults between the ages of 30 and 60 years. It is also seen in older people but is usually less severe. In infants, it is very commonly seen and is known as cradle cap.

It is slightly more common in males as compared to females.

The disease is characterized by spontaneous remissions and exacerbations (flare-ups).

Clinical Features

Seborrhoeic dermatitis affects the scalp, face (creases around the nose, behind ears, within eyebrows), and upper trunk.

Typical features include:

Skin flakes (dandruff) on scalp, hair, eyebrows, hair-bearing areas of the face like beard or mustache.
Patches of greasy skin covered with yellow-white flakes or crust.
Red skin with swollen appearance
Itching or burning sensation
In babies, greasy, crusty yellow-brown scaly patches occur on the baby’s scalp (cradle cap or crib cap). The rash may spread to involve the armpit, groin folds, or diaper area (a type of napkin dermatitis). It usually occurs within the first few weeks of life. The condition slowly resolves and disappears by the age of 6 months to one year without any treatment. It is harmless and not itchy. Hence the baby is often undisturbed by the rash, even if it is widespread.
In adults, the disease can come and go throughout the person’s life. Flare-ups can occur with triggers such as cold and dry weather, stress, etc.

cradle cap — Cradle Cap
Image credit: healthjade.net

seborrheic dermatitis in beard region — Seborrheic Dermatitis in the beard region

Common Sites of Involvement

The scalp is the most common site involved.
Other common sites of involvement include the oily areas of the body such as the face, eyebrows, sides of the nose, eyelids, back of ears, chest, skin folds under the arms and legs, groin area, buttocks, or under the breasts.

Causes of Seborrheic Dermatitis

The exact cause is unknown. The following factors are thought to cause seborrheic dermatitis:

Malassezia yeast, (a fungal organism that normally lives on the surface of the skin), is thought to be responsible for causing seborrheic dermatitis. Overgrowth of this fungus and the overreaction of the body’s immune response to it produce an inflammatory reaction that results in skin changes.
Overproduction of oil (sebum) by the skin is thought to act as an irritant that causes the skin to become red, inflamed, and greasy.

Risk Factors and Triggers

Cold and dry weather: the condition usually improves in summer
Oily skin (seborrhoea)
Hormonal changes or certain medical conditions such as psoriasis, acne, rosacea, eating disorders, Parkinson’s disease, epilepsy, alcoholism, recovery from a stroke or heart attack.
Weakened immune system as seen in patients of HIV, organ transplant recipients, or some cancers.
Certain treatments and medications, including psoralen, ultraviolet (PUVA) therapy, interferon, and lithium
Exposure to harsh detergents, soaps, or chemicals
Lack of sleep
Stress

Is Seborrheic Dermatitis Contagious?

The disease is not contagious meaning it can’t spread from one person to another through contact.

Also, it is not a type of allergy, though the skin lesions can look similar to an allergic reaction.

The disease is not caused by poor hygiene.

Diagnosis of Seborrheic Dermatitis

The diagnosis is mainly based on the appearance of skin lesions and the typical sites of involvement.

No blood tests are required to make a diagnosis.

In some cases, skin biopsy may be performed in which a small piece of skin is removed and examined under a microscope. This is not routinely done for every case and is required only in few cases to exclude other skin conditions having a similar appearance.

The following is a list of skin diseases which may have similar features:

Psoriasis. It causes the skin to become red, covered with scales and flakes which may look similar to dandruff. However, the scales of psoriasis are silvery-white and more extensive.
Atopic dermatitis. This causes itchy, red, and inflamed skin on elbows, knees, legs, folds of skin, etc. The disease is known to run in families and may be associated with other allergic disorders like asthma and hay fever (allergic rhinitis).
Rosacea. It results in facial redness with swollen red spots and small visible blood vessels. Scales are not a typical feature of the disease. It most commonly affects middle-aged women with fair skin.
Allergic reaction. Allergy to a substance may result in a red and itchy skin rash.
Systemic lupus erythematosus (SLE). It can cause a butterfly-shaped rash across the middle of the face.

Self–Care Tips and Home Remedies

Use a mild soap or shampoo.
Rinse soap and shampoo thoroughly from the skin and scalp after washing.
Moisturize your skin regularly.
Avoid using hair sprays, gels, or other styling products.
Avoid skin and hair products that contain alcohol as they can aggravate the disease.
Shave off mustache or beard if that area is involved.
Wear loose cotton clothing. Avoid synthetic clothes. Always wear a layer of cotton clothing beneath the woolens in winters so as to avoid skin irritation.
Use anti-fungal creams or anti-dandruff shampoos which are available over-the-counter (don’t need a medical prescription)

Treatment

Anti-fungal medicated shampoos containing 2% ketoconazole or 1% ciclopirox may be used. They need to be used twice weekly. The treatment needs to be continued for at least a month and in some cases even longer.
Shampoos containing ingredients like selenium, zinc pyrithione, or salicylic acid may also be used.
Lotions and ointments containing steroids (hydrocortisone, fluocinolone, or desonide) may be applied to the scalp. They help to reduce inflammation and itching. Though very effective in controlling symptoms, they should not be used for a prolonged period as they may cause side-effects.

Topical calcineurin inhibitors such as tacrolimus may be used. Although highly effective, it is an expensive treatment.
Coal tar cream can be applied to areas that show scaling followed by removal after a few hours by shampooing.

Cradle cap usually doesn’t require medical treatment as it resolves on its own by the age of 6 months to 1 year. Home remedies are all that is required. These include:

Regularly washing the baby’s hair using a mild shampoo.
Rinsing the hair and scalp thoroughly after shampooing.
Brushing the baby’s hair with a soft-bristled brush to loosen the scaly patches.
In addition, gently massaging the scalp with oil also helps to soften and loosen the scaly patches.

Antifungal creams/shampoos or steroid creams are not usually recommended for babies.

Prognosis

In adults, the disease has a waxing and waning course. That means it has a tendency to recur and resolve. Although incurable, the disease can be easily controlled by over the counter and prescription medicines. Prescription medicines should be used just frequently enough to control the symptoms or as advised by the doctor.

References

Zisova LG. Malassezia species and seborrheic dermatitis. Folia Med (Plovdiv). 2009 Jan-Mar. 51(1):23-33.
Ford GP, Farr PM, Ive FA, Shuster S. The response of seborrhoeic dermatitis to ketoconazole. Br J Dermatol. 1984 Nov. 111(5):603-7.
Tatlican S, Eren C, Eskioglu F. Insight into pimecrolimus experience in seborrheic dermatitis: close follow-up with exact mean cure and remission times and side-effect profile. J Dermatolog Treat. 2009. 20(4):198-202.
Schwartz RA, Janusz CA, Janniger CK. Seborrheic dermatitis: an overview. Am Fam Physician. 2006 Jul 1. 74(1):125-30.

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