Atopic dermatitis or atopic eczema is a skin rash that’s particularly common among young children but can last into adulthood, atopic refers to an allergy, dermatitis refers to the skin and itis refers to inflammation so atopic dermatitis describes skin inflammation that results from an allergy, more specifically it happens when the immune system attacks the skin causing a dry itchy rash on flexor surfaces of the body areas like the creases of the wrist, the insides of the elbows and the backs of the knees as well as exposed skin surfaces like on the face, the hands, in the feet when the immune system inappropriately starts attacking itself, we call that a hypersensitivity reaction and there are four types. Atopic dermatitis is a type 4 hypersensitivity reaction and it starts off with something in the environment called an allergen like flower pollen, the pollens are able to travel through the slightly porous skin where it gets picked up by an immune cell in the tissue, just below the immune cell is called an antigen presenting cell because it presents a bit of the allergen to a naive T helper cell activating it into a th to sell this th to cell then stimulates a nearby B cell to start producing IgE or immunoglobulin e antibodies specific to that pollen, those IgE antibodies bind to the surface of other immune cells called mast cells as well as basophils which can be found in the tissue layer just below the skin and this process is called sensitization, now let’s say there’s a second exposure to pollen that makes its way into the skin tissue, now the allergen can cross link the IgE on these sensitized cells resulting in degranulation or release of a number of pro-inflammatory molecules like histamine leukotriene x’ and proteases, the combined effect of these molecules is to cause nearby blood vessels to dilate and become leaky as well as attract even more immune cells to the area creating inflammation of the skin tissue, ultimately this inflammation makes the skin barrier more leaky potentially allowing in more of the allergen while at the same time allowing water to escape leaving the skin dry and scaly, dry skins are very itchy and scratching further damages the skin barrier worsening the process in setting up a vicious cycle of allergy mediated inflammation, dry skin and itching which characterizes atopic dermatitis occasionally, bacteria can invade the damaged skin causing even more inflammation in infants, the rash is most often on the face, in the scalp and in children.
The rash is usually on the flexor surfaces of the extremities, atopic dermatitis can worsen in the presence of allergens like cigarette, smoke, mold and dust mites as well as changes in the weather and even emotional stress, although it usually causes patches of red itchy skin that come and go, the scheme can occasionally even blister and peel over time, the skin can become like Hena fide which literally means turn to leather. Itchiness is often worst at night probably because there are no distractions, this is often when young children are most likely to scratch their eczema lesions because eczema is an autoimmune mediated process, it can’t be spread to other people but since it affects the skin and therefore the way a person looks there’s still a lot of social stigma associated with it. Unfortunately many individuals especially teenagers and young adults with atopic dermatitis suffer from depression and social anxiety as a result, genetics plays an important role in atopic dermatitis and these individuals often also have asthma as well as allergic rhinitis making up what’s called the atopic triad, these illnesses also often run in families occasionally, atopic dermatitis can be part of a syndrome like hyper IgE syndrome which has an autosomal dominant form called Jobe syndrome as well as phenylketonuria which is a metabolic disorder that results from the buildup of the amino acid phenylalanine and wiskott-aldrich syndrome which is an x-linked recessive disease characterized by clinical triad of eczema thrombocytopenia and immunodeficiency. Atopic dermatitis is generally a clinical diagnosis and there are ways to help break the cycle of allergy mediated inflammation, dry skin and itching with regard to allergy mediated inflammation, it’s important to identify and avoid any triggers as well as avoiding overheating, dressing in soft fabrics and managing stress well which is of course a good life habit, anyways dry skin can be managed with frequent moisturization which is usually best to apply after a lukewarm bath and itching can sometimes be managed with simple measures like keeping the fingernails short and trying to keep children from scratching but in more extreme cases there are also steroids and calcineurin inhibitors, both of which aim to dampen the immune reaction as well as antihistamines that can help with itching and antibiotics to help treat infections if they’re needed, all right as a quick recap atopic dermatitis also called atopic eczema is a type 4 hypersensitivity reaction in the skin and is characterized by a cycle of allergy mediated inflammation, dry skin and itching and most commonly affects infants and young children. Atopic dermatitis can be managed by minimizing exposure to allergens, keeping the skin hydrated and minimizing itching.