Atopic Dermatitis

Atopic dermatitis (atopic eczema) is a relapsing, inflammatory, pruritic and eczematous skin disorder.

The disease is related to the following processes:  auto-immune and has an incidence of about  2,100 / 100.000.

Overview

A commonly occurring inflammatory skin disorder, atopic dermatitis, also known commonly as eczema, is a form of allergic reaction to allergens found in the environment. It is frequently described as a cutaneous manifestation of systemic allergic reactions (atopy) [1].

Atopic dermatitis is more common in children and is characterized by excessively dry, red and itchy skin. Various environmental and genetic factors have been implicated in the development of this disease. Although the condition persists over the years, it is not contagious and can be cured with medication.

Etiology

Various genetic and environmental factors are thought to give rise to atopic dermatitis like the following:

  • Individual history of allergic reactions like food allergy, hay fever, asthma, allergic rhinitis, urticaria etc.
  • Autoimmune reactions involving formation of IgE antibodies.
  • Mutations in the filaggrin gene, encoding a transmembrane protein that regulates the water retention mechanisms in the stratum corneum of skin and is essential for maintaining the barrier function of skin.
  • Allergens like dust, chemicals, viruses and other contaminants in the environment.
  • Other skin infections.

Factors like pets, woolen clothing or exposure to pollens are the predisposing factors for the development of this disease.

Epidemiology

In developed countries, the disease is found in 15-30% children and in 2-10% of the adult population. Atopic dermatitis has been linked to living in ‘excessively sanitary’ conditions.

A slight prevalence of disease in females as compared to the males has been reported. All races are equally affected. No specific geographic distribution, other than in pollen dense areas, has been found.

Sex distribution
Age distribution

Pathophysiology

Two different theories have been proposed regarding the pathogenesis of atopic dermatitis [2] [3].

  • The structural and functional abilities of the epidermis are lost as a result of mutations in the filaggrin gene. The barrier function of epidermis is, thereby, impaired and the first line of defense against external agents is lost. Water is lost from the skin, making it dry and itchy.
  • The second theory is centered on the concept of autoimmune reaction occurring in the body. The immune cells like macrophages, Langerhans cells, helper T cells (in the initial stages, Th2 and later, Th1 is involved) inflammatory cytokines, interleukins (IL4, IL5 and tumor necrosis factor) and several other immune mediators are activated as a result of exposure to environmental allergens and give rise to signs and symptoms of inflammation; flare, redness and erythema. All these immune mediators give rise to pruritus. This theory is more widely accepted as compared to the first one.

Prognosis

Presentation

The areas of skin most commonly affected are the skin folds like folds of arms, behind of knees, wrists, face and hands. In children, the extensor surfaces of limbs are commonly involved whereas in adults, usually the flexor surfaces get affected. The patients of atopic dermatitis present with the following clinical features [4] [5]:

  • Skin dryness (xerosis) and redness
  • Raised, eczematous vesicles over the skin
  • Itching (pruritus) that worsens at night, thereby disturbing the sleep pattern of the individual
  • Crusting and scaling of lesions with time
  • Cracking of lesions, making them potential sites for acquiring bacterial (most commonly, the skin colonizer Staphylococcus aureus) viral or fungal infections
  • Other forms of allergy

Of the patients who develop atopic dermatitis before the age of 2 years, 50% are likely to develop other forms of allergic reactions later in life.

Workup

No specific diagnostic tests are available for atopic dermatitis. Patient’s history and examination are helpful in reaching a diagnosis. Serum testing for IgE antibodies can be used to detect ongoing allergic reactions in the body.

It is essential to differentiate atopic dermatitis from other closely related diseases like seborrhic dermatitis on the basis of signs and symptoms and close examination of the manifestations.

Treatment

Conservative treatment of atopic dermatitis includes the following [6]:

  • Anti-inflammatory agents such as topical and systemic corticosteroids are administered. Topical steroids are preferred because they have less systemic side effects. Systemic corticodteroids are used in severe disease.
  • Immunosuppressant drugs may also be given to the patients suffering from atopic dermatitis [7].
  • Topical emollients can also be used and usually have a good outcome [8] [9].
  • Antibiotics are given to prevent secondary bacterial infections in these patients (particularly when immunosuppressive drugs are used).
  • Antihistamines can be used to prevent the allergic mediators from exaggerating this disease.

Surgical measures for atopic dermatitis include the following:

  • Phototherapy with UVA (ultraviolet light with a frequency of 320 to 400 nanometers) or UVB (ultraviolet light with a frequency of 290 to 300 nanometers) is an effective mode of treatment in children as well as in adults [10]. Sometimes both types of ultraviolet light are used.
  • Photochemotherapy consists of phototherapy combined with chemotherapy and is given in patients with more severe disease.

Prevention

The preventive measures against atopic dermatitis include:

  • Observing skin hygiene.
  • Paying special attention to hygiene and sanitary measures in infants and children as they are more likely to acquire to the disease.
  • Avoiding excessive use of skin care products right after taking showers or baths.
  • Avoiding harsh soaps and skin wash products.
  • Frequently washing the bed linens, towels, clothing, utensils etc. to prevent the exposure to dust particles that are commonly found on these items.
  • Keeping the skin adequately hydrated, yet avoiding excessive exposure to moisture.
  • Avoiding scratching the vesicles. The doctor should properly advise the patients in this regard.
  • Avoiding environmental, industrial and occupational allergies.
  • Stress and anxiety have proved to be predisposing factors for atopic dermatitis. Therefore, stress should be avoided.

Patient Information

Atopic dermatitis is a skin disease that affects children the most. Factors causing this disease mainly involve dust particles and other allergic substances present in the environment. It involves excessive dryness, redness and itching over the skin. Atopic dermatitis gives rise to an urge to scratch which should be avoided as much as possible because the eruptions can peel off, exposing the vulnerable ski underneath. This might become a cause of acquiring infections.

The condition is not contagious and is not transmitted from one person to another. These eruptions can be cured with proper care and treatment.

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References

  1. Conde-Taboada A, Gonzalez-Barcala FJ, Toribio J. [Review and update of current understanding of childhood atopic dermatitis]. Actas dermo-sifiliograficas. Nov 2008;99(9):690-700.
  2. Takigawa M, Sakamoto T, Nakayama F, Tamamori T. The pathophysiology of atopic dermatitis. Acta dermato-venereologica. Supplementum. 1992;176:58-61.
  3. Kang K, Stevens SR. Pathophysiology of atopic dermatitis. Clinics in dermatology. Mar-Apr 2003;21(2):116-121.
  4. Guillet G. [Atopic dermatitis:epidemiologic, clinical features, the role of allergy (review)]. Allergie et immunologie. Dec 2000;32(10):393-396.
  5. Oakes RC, Cox AD, Burgdorf WH. Atopic dermatitis. A review of diagnosis, pathogenesis, and management. Clinical pediatrics. Jul 1983;22(7):467-475.
  6. Correale CE, Walker C, Murphy L, Craig TJ. Atopic dermatitis: a review of diagnosis and treatment. American family physician. Sep 15 1999;60(4):1191-1198, 1209-1110.
  7. Naeyaert JM, Lachapelle JM, Degreef H, de la Brassinne M, Heenen M, Lambert J. Cyclosporin in atopic dermatitis: review of the literature and outline of a Belgian consensus. Dermatology. 1999;198(2):145-152.
  8. Yun Y, Kim K, Choi I, Ko SG. Topical herbal application in the management of atopic dermatitis: a review of animal studies. Mediators of inflammation. 2014;2014:752103.
  9. Simpson EL. Atopic dermatitis: a review of topical treatment options. Current medical research and opinion. Mar 2010;26(3):633-640.
  10. Meduri NB, Vandergriff T, Rasmussen H, Jacobe H. Phototherapy in the management of atopic dermatitis: a systematic review. Photodermatology, photoimmunology & photomedicine. Aug 2007;23(4):106-112.

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