Dermatology

Atopic Dermatitis- Eczema


https://en.wikipedia.org/wiki/Dermatitis

A 3 year old comes to your clinic with the chief complaint of a rash on the back of the hands. There are some papules on the extensor surface of the forearms as well. According to the parents the child is very irritable especially at night. There is a strong family history of atopy.

What is the most common etiology for this rash?

Epidemiology 

  • The incidence and prevalence of atopic dermatitis (AD) have increased in the United States and worldwide, particularly in developed nations.
  • Fewer than 10% of children were affected in the 1970s, but recent epidemiologic studies estimate that 15% to 20% of children are diagnosed with AD. The reason for the increased rate is unknown.
  • 60% of patients with AD will manifest symptoms in the first year of life and 90% by age five.

Pathophysiology 

  • Manifestations of AD are believed to be due to the interaction of certain genes, the environment, and immunologic response to the environment and specific trigger factors. 

  • In acute AD lesions, T-helper 2 (TH2) cells are present in larger numbers than normal and have increased expression of specific cytokines that, in turn, stimulate B cells to produce IgE, resulting in peripheral eosinophilia.

  • Cytokines and chemokines are released from cells in the skin, attracting other inflammatory cells and producing inflammatory mediators and reactions.

  • Keratinocytes, Langerhans cells, endothelial cells, monocyte-macrophages, and eosinophils all play roles in the acute and chronic inflammation of AD.

Diagnosis

  1. Pruritis- Eczema is the "itch that rashes" 
  2. Distribution
  3. Chronic recurring course
  4. Strong family history of atopy

Infantile Eczema - usually presents after 6-8 weeks of life and most commonly on the face, forehead, chest, and extensor surfaces of the extremities. There is erythematous exudative patches. The children are often very irritable and sleep poorly because of itching.

Childhood Eczema - Distribution on the face, flexor surfaces including the antecubital and popliteal areas. May involve the neck, back, ankles, and wrists. Chronic lesions become thickened and dry. Intense pruritis. 

Associated Conditions

  1. Increased incidence of contact dermatitis because of compromised stratum corneum
  2. Increased incidence of molluscum, warts, and herpes viral infections 
  3. Secondary Staphylococcus and Candida infections. 
  4. Eczema herpeticum- rapid replication of viruses with systemic manifestations and possible death. Can also occur with chickenpox.
  5. Cataracts
  6. Emotional problems secondary to constant care, frequent physician visits, missed school and resultant poor academic progression, tension in families secondary to poor sleeping and an irritable child, and an inability to participate in sports.

Differential Diagnosis

  1. Seborrheic Dermatitis- usually younger onset, different distribution, and not pruritic
  2. Scabies- may be difficult to differentiate in infants because distribution may mimic eczema. Other family members with rash may help in the diagnosis.
  3. Contact dermatitis
  4. Numular eczema
  5. Tinea infections
  6. Histiocytosis
  7. Wiscott Aldrich Syndrome

Treatment

  1. Avoid irritants and soaps. Suggest Dove, Tone, and Alpha keri if soaps are used
  2. Avoid aggravating situations
    1. Dry skin
    2. Sweating
    3. Certain fabrics such as wool.
    4. Foods and inhalants that have been identified that aggravate the condition.
    5. Pets
  3. Hydration-suggest applying occlusive substance like petroleum jelly after shower or bath to help keep moisture in the skin. This improves the barrier function of the skin. May also use moisturizer one hour after applying topical steroids. Some examples include Aquaphor, Eucerin, Cetaphil, petroleum jelly and vegetable oils.
  4. Topical steroids- Reduces inflammation and decreases pruritis. Generally avoid the use of potent topical steroids especially on the face, diaper area, inguinal, and axillary area because these are areas where the skin is thin and absorption is high. The lowest potency topical steroid that is effective should be used. More potent steroids may be necessary for short periods but the face should be avoided.  Low strength useful on the face include alclometasone.  Moderate strenth useful on the body include triamcinolone, fluocinonide, mometasone.
  5. Systemic Therapy- may need to use systemic antibiotics to treat superinfection with Staphylococcus. Antihistamines may be helpful for their sedative effects and/or decreasing itching. Systemic steroids should not be used because of their side affects and severe rebound. 
  6. If the child is not responding to the usual therapeutic modalities, hospital admission may be necessary to remove from contact with allergens, assure compliance, educate the families, and reduce familial stress.
  7. Topical Tacrolimus-an immunosuppressant that may be useful if there is a poor response to topical steroids.  Long-term safty profile not yet established.  No present evidence that it causes systemic immunosuppression.
  8. Bathing- 5-10 minute baths or showers followed by blot drying can be beneficial.  This should be followed by application of moisturizers.This also helps eliminating pathogens like S. aureus and allows better penetration of topical medications.
  9. Antihistamines for itching- Suggest non-sedating so that they can be used during the daytime.  Citirizine(Zyrtec), loratidine, fexofenadine

Complications of Topical Steroids

  1. Thinning of the skin with redness and poor wound healing. Development of telangectasias.
  2. Proliferation and obstruction of sebaceous glands
  3. Striae formation (shoulders, hips, and breasts)
  4. Combination products like Mycolog and Lotrisone contain very potent steroids and should be avoided in pediatrics.

References

  1. Epps, Roselyn. Atopic Dermatitis and Ichthyosis. Pediatrics in Review. 2010; 31:278-286 
  2. Friedlander SF. Consultation with the Specialist: Contact Dermatitis. Pediatrics in Review. 1998; 19:166-171.
  3. Halbert, Anne. The Practical Management of Atopic Dermatitis in Children. Pediatric Annals. February 1996
  4. Knoell KA and Greer KE. Atopic Dermatitis. Pediatrics in Review. 1999; 20:46-52.
  5. Lapidus, Candace S. and Honig, Paul J. Atopic Dermatitis. Pediatrics in Review. August 1994.
  6. Wahn U. Efficacy and Safety of Pimecrolimus in Long-term Management of Atopic Dermatitis Pediatrics. July 2002
  7. Williams H.C. Atopic Dermatitis. NEJM June 2, 2005
  8. Krakowski A et al. Management of Atopic Dermatititis in the Pediatric Population. Pediatrics Oct 2008
  9. Shaw M, Burhart C, Morrell D. Systemic Therapies for Pediatric Atopic Dermatitis: A Review for the Primary Physician.  Pediatrics Annals 2009 Vol 38 Number 7