By: Jennifer Bahney for The Trichological Society’s College of Trichology
The word “eczema” comes from the Greek word for “to boil over.” It applies to a broad range of skin conditions and is most commonly considered a form of dermatitis, a condition causing the epidermis (outer layer of skin) to become inflamed in the form of a rash. For this reason, eczema may also be called dermatitis eczema and eczematous dermatitis.
In some languages, dermatitis and eczema are often one in the same. In still other languages, dermatitis is considered to be an acute condition (one that is treatable) and eczema to be a chronic condition (a prolonged condition that requires long-term management).1
Symptoms include dry and recurring skin rashes with redness, swelling, itching, crusting, flaking, blistering, cracking, oozing, or bleeding. Excessively scratching an eczema lesion may lead to infection and scarring.2
In 2001, the European Academy of Allergology and Climincal Immunology (EAACI) simplified the nomenclatures for allergy-related eczemas:3
- Atopic eczema (also, atopic dermatitis): An allergic disease believed to run in families where members also have asthma. Characterized by an itchy rash on the head, scalp, neck, inside of elbows, behind knees, and buttocks.
- Contact dermatitis: Can be caused by an allergic reaction to an allergen like poison ivy, or an irritant such as a harsh detergent. Usually curable once the offending substance is removed from skin contact.
- Xerotic eczema (“Winter Itch”): Itchy, dry skin on the limbs and trunk due to cold, dry weather. Lesions may resemble a cracked river bed.
- Seborrhoeic dermatitis (“cradle cap” in infants): Closely related to dandruff. Causes dry or greasy peeling of the scalp, eyebrows and face. Can also appear in skin folds in the arms, legs, breasts, etc. Cradle cap in infants results in a thick, crusty, yellowish scalp rash that is not harmful but may be related to biotin deficiency.
Less common eczemas include:
- Dyshidrosis: Occurs as tiny opaque bumps (“vesicles”) on the palms, soles of feet, and sides of fingers and toes. Can become worse at night and in warm weather.
- Discoid eczema: Presents as round spots of rash that can be oozing or dry. Often appears on the lower legs and can be worse in winter.
- Venous eczema: Redness, scaling, and itching often appears in the ankle area of older people with impaired circulation including varicose veins and edema. Often predisposes leg ulcers.
- Dermatitis herpetiformis (Duhring’s Disease): Causes an itchy, symmetrical rash on arms, thighs, knees, and back. Directly related to celiac disease and can be managed with proper diet.
- Neurodermatitis (lichen simplex chronicus): Itchy patches of thickened skin resulting from constant rubbing and scratching. Curable through behavior modification and anti-inflammatory medication.
- Autoeczematization: Itchy patches caused by a parasitic, fungal, bacterial, or viral infection. Curable with the infection’s eradication.
Eczemas may also be the result of underlying diseases such as lymphoma, and from reactions to ingested medications, foods, and chemicals.
Seborrheic dermatitis on the scalp may be caused by an overproduction of sebum. The resultant greasy scales may lead to an overgrowth of normal skin fungus called Mallasezia (previously called pityrosprum), which causes flakes known as dandruff. Seborrheic dermatitis frequently extends beyond the hair onto the forehead, behind the ears, and onto the neck, including a man’s beard.4 Seborrheic dermatitis of the scalp will only cause harm if the patient’s excessive scratching breaks the skin and leads to infection. According to Olsen, severe seborrheic dermatitis may be accompanied by mild to moderate telogen effluvium (excessive shedding of scalp hair).5
The cause of seborrheic dermatitis is unknown but may be dependent on androgen production and sebaceous activity. Babies with SD often have a recurrence of the condition in adolescence and early adulthood when sebaceous activity is active. In addition, patients with Parkinson’s disease, cerebovascular accidents, head trauma and epilepsy often have elevated sebum excretion plus a higher incidence of SD.6 According to Olsen, the cause of abnormal sebum production may be due to abnormalities in the stratum corneum, with poor adhesion of keratinocytes and excessive intercellular lipid shouldering the blame.
On the scalp, seborrheic dermatitis is often treated by removing the scales, reducing inflammation, and reducing the presence of yeast. Medicated shampoos that include zinc pyrithione (anti-fungal, anti-bacterial), salicylic acid (anti-inflammatory), or ketoconazole (anti-fungal) are helpful, as are anti-fungal agents sulfur and selenium sulfide. Topical creams or sprays from coal tar or coticosteroids (such as hydrocortisone acetate 1% cream) are also used to calm irritation and flaking.
In Disorders of Hair Growth, Elisa A. Olsen suggests that frequent shampooing of the scalp with 2% ketoconazole shampoo followed by a topical corticosteroid (every day or every other day, depending on potentcy) plus antibiotics if a secondary bacterial infection is detected. Once the seborrheic dermatitis is controlled, she recommends regularly alternating between non-medicated and medicated shampoos.
When a baby has seborrheic dermatitis on the scalp, it is more commonly called cradle cap (vernix caseosa). According to Olsen, maternal androgens and aberrations in free fatty acids may play a role in the development of cradle cap.7Cradle cap may begin in utero and often dissipates by the baby’s first birthday. It appears as oily, yellow scaling or crusts on the baby’s scalp and is the result of a buildup of sebum and sloughed skin cells.
Cradle cap can be treated with the following routine:
- Gently rub baby’s scalp with vegetable oil to help loosen scales.
- Wet baby’s head, then gently scrub scales with a soft bristle brush to remove the scales.
- Wash scalp with a mild baby shampoo (dandruff shampoos are too harsh for baby’s skin), then gently blot dry.
Although cradle cap isn’t harmful, it may be stubborn to clear up. In such a case, a prescription cream or shampoo may be recommended by a doctor after a thorough pediatric exam.
Although there is no known cure for eczema, steps can be taken to lessen flare-ups. Adult patients should:
- Avoid exposure to irritants and allergens they suspect may trigger the disease.
- Clean the scalp with a medicated shampoo and warm water (hot water may trigger a flare-up), especially after physical exertion.
- Avoid excessive stress.
Dawber, Rodney, Ed., Diseases of the Hair and Scalp, Third Edition, Blackwell Science, Malden, MA, 1997.
Olsen, Elisa A.,Ed., Disorders of Hair Growth, Second Edition, McGraw-Hill, New York, 2003.
1. Wikipedia.org, Dermatitis, http://en.wikipedia.org/wiki/Dermatitis.
2. Wikipedia.org, Eczema, http://en.wikipedia.org/wiki/Eczema.
3. Wikipedia.org, Eczema, http://en.wikipedia.org/wiki/Eczema.
4. Olsen, Elise, Disorders of Hair Growth, p. 105.
5. Olsen, Elise, Disorders of Hair Growth, p. 105.
6. Olsen, Elise, Disorders of Hair Growth, p. 105.
7. Olsen, Elise, Disorders of Hair Growth, p. 105.