These recent molecular discoveries provide new insights
into atopic dermatitis and how skin inflammation, T-cell mediated
hypersensitivity is associated with allergic conditions with immediate
hypersensitivity such as asthma and allergic rhinitis (hay fever). A defect in
the epidermal skin barrier due to filaggrin mutations explains the Techqueer development
of xerosis and a predisposition to skin irritation manifested as atopic
dermatitis; however, they are not mediated by allergic mechanisms. In contrast,
skin inflammation is a delayed-type T-cell mediated hypersensitivity and
includes a dominant Th2 component in the skin. This hypersensitivity suppresses Digitalknowledgetoday the activity of antimicrobial peptides (eg, beta-defensins), which explains the
predisposition of patients with atopic dermatitis to develop bacterial and
viral skin infections. Increased penetration of skin irritants and allergens
also leads to Th2-dominant inflammation, which also stimulates IgE production
and predisposes to immediate hypersensitivity. However, since the main
mechanism mediating atopic dermatitis is delayed cellular immunity, avoiding
immediate-type allergens (eg, pollen, dust mites) does not usually help with
atopic dermatitis. Although Healthnutritionhints immediate-type hypersensitivity (eg, asthma,
allergic rhinitis) is the result of a defect in the skin barrier, they do not
cause skin T-cell inflammation of atopic dermatitis.
In patients with atopic diathesis, atopic dermatitis
usually precedes allergic rhinoconjunctivitis and asthma. This Smartdiethealth sequence is
sometimes called the "atopic march" and arises from the fact that a
defect in the skin barrier is the main deficiency in atopic conditions.
Pathophysiology reference
In the acute phase, the lesions are scaly, reddened,
thickened, Healthfitnesschampion severely itchy patches or plaques that may collapse when scratched.
In the chronic phase, scratching and rubbing produces
dry, lichen-like skin rashes.
The spread of the lesions depends on age. In infants,
lesions usually appear on the face, scalp, neck, eyelids, and extensor surfaces
of the extremities. In older children and adults, injuries occur on flexion
surfaces such as the neck, anterobital fossa, and popliteal fossa.
Severe itching of the skin is a key feature. Itching
often precedes injuries and is aggravated by dry air, sweating, local
irritation, woolen clothing, and emotional stress.
Common triggers for environmental symptoms include:
Bathing or washing
excessively
Strong soap
Colonization of
the skin with Staphylococcus aureus
Perspiration
Rough fabrics and
wool
Complications
Secondary bacterial infections (superinfections) are
common, especially staph and streptococcal infections (eg, impetigo,
cellulitis). Erythroderma (erythema covering more than 70% of the body surface)
is rare, but can occur with severe atopic dermatitis.
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