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EczemaNet February Update
Nummular Eczema and Heat,
Humidity and Emotional Stress as Triggers for Atopic Dermatitis
Nummular eczema is a puzzling disease with
at least three names: (1) nummular eczema, the most commonly used name,
(2) nummular eczematous dermatitis, a longer and more medically
descriptive name, and (3) discoid eczema, a name derived from the disease’s
typical coin-shaped lesions seen in this photo:
Typical coin-shaped lesions
of nummular eczema on the back of a patient’s hand.
(Photos in this Update used
with permission of the American Academy of Dermatology National Library of
Dermatologic Teaching Slides and the Sulzberger Institute for Dermatologic
Education)
The cause or causes of nummular eczema are
not known with certainty, but many different causes have been suggested. A
number of factors, acting alone or in combination, may be suspected—for
example, dry skin in indoor and outdoor environments with low humidity;
isotretinoin; and bacterial infections that induce a hypersensitivity
reaction in skin.
Factors that may cause worsening of
nummular eczema include wool clothing worn next to the skin, topical
medications, soaps and detergents, and frequent bathing (as seen in this
photo):
Red, crusted nummular eczema
lesions on the ankle of a patient who bathed with vigorous rubbing several
times a day.
Nummular eczema characteristically appears
first as a group of tiny red spots (papules) and blister-like lesions
(vesicles) that enlarge and merge into a reddened, itchy, sometimes
burning coin-shaped lesion two to 10 centimeters in diameter. The lesion
may be uniformly red at first, then clear in the center to form a
"ring" that resembles the fungal infection called ringworm.
New, acute lesions are likely to
"weep" edematous fluid that dries into crusts. Chronic,
persisting lesions are scaly.
An outbreak of nummular eczema may begin
with one or several lesions. Some patients experience spontaneous clearing
of lesions within a year. In other patients the lesions persist or recur
for many years; lesions that recur after clearing tend to do so at the
sites of the original outbreak.
The most common sites for nummular eczema
are the legs (most common), arms and hands, and the torso. The disease is
more frequent in men than in women, with a peak age of onset at 55 to 65
years. A smaller peak has been observed in women 15 to 25 years old.
Since the cause of nummular eczema is
unknown, treatment is largely directed at relief of the major symptoms of
itching and burning. Treatment should be prescribed by a dermatologist
after a diagnosis of nummular eczema is confirmed. Baths with oil
additives, and regular application of emollients can keep the skin from
becoming excessively dry. Tar preparations and topical anti-inflammatory
steroid agents may be prescribed to reduce inflammation and itching. Skin
infection may be treated with prescribed antibiotics. Anti-histamines or
ultraviolet phototherapy may be prescribed. Oral steroids may also be
prescribed in severe cases that are resistant to other forms of treatment.
References
Sotor NA. Nummular eczematous eczema. In:
Freedberg IM et al (eds.) Fitzpatrick’s Dermatology in General Medicine,
5th ed. New York: McGraw Hill; 1999:1480-1482.
Jarvikallio A, Naukkarinen A, Harvima IT et
al. Quantitative analysis of tryptase- and chymase-containing mast cells
in atopic dermatitis and nummular eczema. Br J Dermatol 1997; 136:871-877.
Heat, Humidity and Emotions as Triggers
for Atopic Dermatitis
Excessive heat, high humidity, excessively
dry air and emotional stress are mild annoyances for most people, but for
a person with atopic dermatitis (AD) they may be triggers for worsening
symptoms. Persons with AD are more sensitive to irritants than are people
without AD. The list of potential irritants is long, including soaps and
detergents, scratchy clothing, many chemicals, extremes of heat and
humidity and emotional stress. The effect of irritants in AD is to
initiate reactions in the skin that worsen the itch-scratch cycle. No
single factor is an irritant for all people with atopic dermatitis, but
most people are sensitive to one or more of the long list of irritants.
Atopic dermatitis patients who are
sensitive to heat and humidity may have to reduce exposure to outdoor
extremes of both. They also may have to take measures to control indoor
heat and humidity. A case-control study by McNally et al (see references)
found a statistically significant association between AD symptoms in
children and excessive humidity in the home as well as excessive heat and
dryness when a radiator was used to heat the patient’s bedroom.
The relationship between emotional stress
and triggering of symptoms is not clear. While some female patients have
felt that AD symptoms may worsen before or during menstruation, there is
no evidence that hormones are a trigger for atopic dermatitis.
Frustration, embarrassment and anger have been identified by patients as
emotional events that can worsen the itch-scratch cycle. A study by
Ginsburg et al (see references) of emotional factors in 34 adults with AD
found that they felt anger more readily but were less effective in
expressing anger than were persons without atopic dermatitis. Links
between emotional stress and regulation of immune reactions in skin are
not well understood and require more investigation.
References
Ginsburg IH, Prystowsky JH, Kornfeld DS,
Wolland H. Role of emotional factors in adults with atopic dermatitis. Int
J Dermatol 1993; 32:656-660.
McNally NJ, Williams HC, Phillips DR.
Atopic eczema and the home environment. Br J Dermatol 2001; 145:730-736.
Nassif A, Chan SC, Storrs FJ, Hanifin JM.
Abnormal skin irritancy in atopic dermatitis and in atopy without
dermatitis. Arch Dermatol 1994; 130:1402-1407.
Ohmen JD, Hanifin JM, Nickloff BJ et al.
Overexpression of IL-10 in atopic dermatitis. Contrasting cytokine
patterns with delayed-type hypersensitivity reactions. J Immunol 1995;
154:1956-1963. |
