Atopic dermatitis

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Atopic dermatitis


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Atopic dermatitis

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A 12-month-old boy is brought to the emergency department because of a painful vesicular rash on his face, elbows, and trunk for two days. His parent states the patient had a “flare-up of dryness and itching” in the same region for which high-potency topical corticosteroids were started five days ago. Family history is significant for asthma in his mother. Temperature is 38.05°C (100.5°F), pulse is 130/min, respirations are 20/min, and blood pressure is 110/70 mmHg. Physical examination shows an irritable child with erythematous, scaly, crusted lesions on the extensor surfaces of the elbows and on the trunk. Examination findings of the face are shown:

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The presentation of this patient is most likely a complication of which of the following?

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Asthma p. 698

eczema and p. 489

Atopic dermatitis (eczema) p. 489


B-complex deficiency p. 63

glucagonomas p. 359

IPEX syndrome p. 100

type IV hypersensitivity reaction p. 111

vitamin B5 deficiency p. 65

vitamin B7 deficiency p. 66


hyper-IgE syndrome p. 114, 716

phenylketonuria p. 82

type I hypersensitivity p. 110

Wiskott-Aldrich syndrome p. 115, 720

Eczema (atopic dermatitis)

atopic dermatitis p. 489

Eczematous dermatitis p. 487

Food allergies and eczema p. 489

IgE antibodies p. 103

eczema p. 489


eczematous patches p. 674


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, “derm” 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 wrists, the insides of the elbows, and the backs of the knees, as well as exposed skin surfaces like on the face, the hands, and 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 1 hypersensitivity reaction, and it starts off with something in the environment called an allergen, like flower pollen.

The pollen is 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 Th2 cell.

This Th2 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 surface of the skin, and this process called “sensitization”.


  1. "Robbins Basic Pathology" Elsevier (2017)
  2. "Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2)" McGraw-Hill Education / Medical (2018)
  3. "Pathophysiology of Disease: An Introduction to Clinical Medicine 8E" McGraw-Hill Education / Medical (2018)
  4. "Atopic Dermatitis: Skin-Directed Management" Pediatrics (2014)
  5. "Management of difficult and severe eczema in childhood" BMJ (2012)

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