Tuesday, December 27, 2011

Atopic Dermatitis : Diagnosis & Pathogenesis

Cases in Atopic Dermatitis Medscape Pediatrics CME Lawrence F. Eichenfield, MD Professor of Clinical Pediatrics and Medicine (Dermatology), University of California Pathogenesis and Diagnosis of Atopic Dermatitis Atopic dermatitis (AD) is a common inflammatory skin disorder affecting 10%-20% of children during their first decade of life. It is characterized by a pruritic, scaling rash that follows a fluctuating course. In approximately 60% of patients, AD starts in the first year of life. Newborns and infants usually have involvement on the cheeks, chin, and extremities. As the child ages, the rash typically transitions to classic involvement of the flexural antecubital and popliteal fossae. Fortunately, AD frequently resolves when the patient grows older. The pathogenesis of AD is complex and multifactorial. Acute AD is characterized by strong type 2 T-helper (TH2) cell responses with production of interleukin (IL)-4, IL-5, and IgE antibodies, whereas chronic AD has immunologic features more consistent with TH1-mediated responses. Recent evidence also suggests a possible role for TH17 cells. There is a significant barrier defect in people with AD. Many have mutations in the epidermal proteins that result in epidermal barrier dysfunction. The epidermis of skin affected with AD often has decreased levels of filaggrin, a protein responsible for aggregation and adhesion of the cornified envelope; ceramides, the predominant lipids of the cornified envelope; and antimicrobial peptides, such as beta-defensins and cathelicidins, proteins of the innate immune system that resist cutaneous colonization and infection. Further exacerbating the epidermal barrier of people with AD is increased transepidermal water loss. As a result of these barrier defects, allergen absorption and bacterial colonization and infection are enhanced, which further potentiates the immunologic dysfunction present in skin affected by AD. The diagnosis of AD is usually not challenging. However, other diagnoses should be considered if the presentation is atypical. Differential diagnoses include scabies, psoriasis, allergic contact dermatitis, immunodeficiency diseases, metabolic conditions, nutritional disorders, Langerhans cell histiocytosis, and various other disorders as suggested by the patient's presentation. Because AD is part of an atopic triad that includes asthma and allergic rhinitis, it is important to ask patients and parents whether there is a history of any of these in the patient or family. If there is such a history, AD is more likely. A child has a 20% risk for AD if one parent is affected and a 50% risk if both parents are affected. Furthermore, the concordance rate between monozygotic twins is 80%, and the concordance rate between dizygotic twins is 20%. Findings on physical examination that support a diagnosis of AD include typical pruritic eczematous dermatitis, hyperlinear palmar dermatoglyphics (increased fine skin lines), Dennie-Morgan fold (infraorbital line caused by edema), allergic shiners (dark periorbital skin due to sinus congestion and venous congestion), allergic salute (horizontal crease on the dorsal nose secondary to chronic allergies and rubbing), keratosis pilaris (spiny papules on the anterolateral upper arms), and ichthyosis vulgaris (fish-like scales on the skin). The diaper area of infants and toddlers with AD is characteristically spared, partially due to the occlusive hydration effect of diapers. The presence of significant rash in this area should prompt the consideration of other etiologies. There are many proposed diagnostic criteria for AD. Perhaps the most practical, sensitive, and validated for use in epidemiologic studies are the UK Working Party's Diagnostic Criteria for Atopic Dermatitis (Table 1). To meet these criteria, the patient must have pruritus and 3 or more minor criteria. Table 1. UK Working Party's Diagnostic Criteria for Atopic Dermatitis A. Required Criterion 1. Pruritus B. Minor Criteria (≥ 3 of the following must be present) 1. Onset < 2 years of age 2. History of flexural involvement 3. History of asthma or hay fever (or history of these conditions in parent or sibling if patient is < 4 years of age) 4. History of general dry skin in the last year 5. Visible flexural eczema (or eczema involving the cheeks/forehead and outer limbs in children < 4 years of age) Similarly, the American Academy of Dermatology Consensus Conference stated that AD is best thought of as a syndrome with features classified as "essential," "important," and "associated" (Table 2). Table 2. American Academy of Dermatology Consensus Conference Definition of Atopic Dermatitis A. Essential Features (must be present) 1. Pruritus 2. Eczema (acute, subacute, chronic) a. Typical morphology and age-specific patterns* b. Chronic or relapsing history B. Important Features (seen in most cases, adding support to the diagnosis) 1. Early age at onset 2. Atopy a. Personal and/or family history b. IgE reactivity 3. Xerosis C. Associated Features (helpful in suggesting the diagnosis but too nonspecific for defining or detecting AD for research or epidemiologic studies) 1. Atypical vascular responses (eg, facial pallor, white dermographism, delayed blanch response) 2. Keratosis pilaris/hyperlinear palms/ichthyosis 3. Ocular/periorbital changes 4. Other regional findings (eg, perioral changes/periauricular lesions) 5. Perifollicular accentuation/lichenification/prurigo lesions Exclusionary Conditions Diagnosis of AD depends on excluding such conditions as scabies, seborrheic dermatitis, allergic contact dermatitis, ichthyosis, cutaneous lymphoma, psoriasis, and immune deficiency diseases * Patterns include (1) facial, neck, and extensor involvement in infants and children; (2) current or prior flexural lesions in any age group; and (3) sparing of groin and axillary regions.


Anonymous said...

Αhaa, its nicе discussion cоncerning this article here at this
web sіte, ӏ have гead all that, ѕo at this time me alѕo
commenting herе.

Fеel fгee to surf to my web page: tens
My web page > tens unit

Anonymous said...

Hi theгe it's me, I am also visiting this web page regularly, this website is actually good and the people are really sharing pleasant thoughts.

my web blog :: Www.Samstensunits.Com

Anonymous said...

Howdy just wаnted to giνе you a quіck heaԁs up.
Τhе teхt in уour cοntent
seem to be running off the screеn in Chrоme.
I'm not sure if this is a formatting issue or something to do with internet browser compatibility but I thought I'd pоst to let
you know. Thе design look gгeat though! Hope you
get the problem solνed soon. Thanks

Heгe is my websіte ... how to make money buying and selling cars for profit

Anonymous said...

Maу І simply just say what a comfort tο discοver someone who truly understands ωhat thеy're talking about online. You definitely realize how to bring a problem to light and make it important. More and more people really need to read this and understand this side of your story. I was surprised that you aren't more popular given thаt you surely pοssеsѕ the gіft.

Feel free to surf to my weblog - seo frisco tx

Anonymous said...

Whаt's Going down i am new to this, I stumbled upon this I have discovered It positively useful and it has helped me out loads. I am hoping to contribute & help other customers like its aided me. Good job.

Here is my weblog ... dfw seo specialists

Anonymous said...

Ηey I аm so ехcited I found your ωebsite, I
гeally found yоu bу acсident, whіlе
I ωaѕ searching οn Goοgle fοг something else, Regardleѕs Ӏ
am hеre nоw and would juѕt liκe to say thanks for a mаrvelοus post and a all rounԁ intereѕting blog (I alsο lοve the theme/design), Ι don’t haѵe time tο broωse it all at the moment but I
hаѵe savеd it anԁ alѕo added іn уour
RSS feeԁs, so when I havе time I will be bасk to read much morе, Pleasе ԁo κeep uρ
the ѕupeгb work.

my ωеb-site ... page1rankingdallas.com

Anonymous said...

Great post. I was checking constantly this blog and I am impressed!
Extremely helpful information specially the last part
:) I care for such info a lot. I was seeking this particular information for a very long time.
Thank you and good luck.

Also visit my blog post ... buy real Youtube subscribers

Anonymous said...

Taking family strolls or even sitting down to eat dinner together to discuss the day's events all help to increase the strength of a family.
The experts at the Chapel Hill Tubal Reversal Center work with women who want to have a tubal reversal surgery on a daily basis.

Anonymous said...

hello there and thank you for your information ? I have definitely picked up something new from
right here. I did however expertise a few technical points using this site, as I experienced to reload the website lots of times
previous to I could get it to load properly. I had been
wondering if your web hosting is OK? Not that I'm complaining, but slow loading instances times will often affect your placement in google and can damage your quality score if ads and marketing with Adwords. Anyway I'm adding this RSS to
my e-mail and can look out for a lot more of your respective interesting content.

Make sure you update this again very soon.

Feel free to visit my blog post ... Click Here