Topic Learning
Dermatitis/Eczema - denoting a polymorphic inflammatory reaction pattern involving the
epidermis and dermis.
Atopic Dermatitis VS Contact Dermatitis
Atopic Dermatitis
Epidemiology:
- Very common to start in infancy, some by age 5, and 10% between 6 to 20 yrs old.
Personal history:
- with a personal or family history of AD, allergic rhinitis, and asthma; (picture)
-
35% of infants with AD develop asthma later in life.
Associated with skin barrier dysfunction - due to impaired filagrin production, reduced
ceramide levels, and increased trans epidermal water loss; dehydration of skin.
Eliciting or Triggering Factors:
- Aeroallergens: dust mites, dust, pollens, animal dander/pet fur, carpets
- Food: eggs, milk, peanuts, soybeans, fish, wheat, seafood.
- Season: cold weather then sudden hot weather
-
Clothing: pruritus AFTER taking clothing off (picture),
-
o
wool clothing
Emotional stress: can result from the disease or itself an exacerbating factor to more
flare ups.
Pathogenesis
Complex interaction of skin barrier, genetic, environmental, pharmacologic, and
immunologic factors. Type I (IgE-mediated) hypersensitivity
reaction occurring as a result of the release of vasoactive substances from both mast cells and
basophils that have been sensitized by the interaction of the inflammation in AD shows a
biphasic pattern of T-cell activation.
Clinical Manifestation: (Character of the skin)
- Dry skin
- Pruritus –
- Itch scratch cycle – vicious
- Acute (less than 6 months) – erythematous patches, papules, plaques
o (picture) 2-12, 2-13,
o
o
o consequent rubbing leads to increased inflammation and lichenification (picture)
and to further itching and scratching leading to chronic AD.
-
Chronic (more than 6 months, YEARS)
o Picture (2-14, 2-17
Distribution: (2-16, 2-17A B)
o Flexures
o front and side of the neck
o forehead
o face
o wrists
o dorsum of feet and hands
Diagnosis
- Medical History and clinical findings
Laboratory Examinations
- Bacterial Culture
- Viral Culture
- Blood Studies
- Dermatopathology
Course and Prognosis
- In many patients, the disease persists for 15–20 years, but is less severe. Thirty to fifty
percent of patients develop asthma and/or hay fever.
Management
- Baseline therapy of dryness with emollients
- Picture of management
-
Contact Dermatitis
Irritant Contact Dermatitis VS Allergic Contact Dermatitis
Irritant – caused by chemical irritant
Allergic – caused by an allergen – delayed and with immunologic reaction.
Epidemiology:
- Can happen to anyone and at any age.
Predisposing Factors:
- Atopic Dermatitis
- Fare Skin
- Cold weather
- Humid weather
- Occlusion
- Mechanical Irritation
Irritants or Allergens:
- Abrasives, cleaning agents,
- oxidizing agents; reducing agents,
- plants and animal enzymes, secretions;
- desiccant powders, dust, soils;
- excessive exposure to water.
Clinical Manifestation: (Character of the skin)
IRRITANT CONTACT
- Burning, stinging – can occur within seconds (immediate-type stinging), or can be
delayed up to >24 hrs.
- Erythema or vesiculation (picture)
- Sharply demarcated and superficial edema
- LESIONS DO NOT SPREAD BEYOND SITE OF CONTACT.
ALLERGIC CONTACT
- Less likely to be itchy
- Itch scratch cycle – vicious
- Acute (less than 6 months) – erythematous patches, papules, plaques
o (picture) 2-12, 2-13,
Diagnosis
- Medical History and clinical findings
Laboratory Examinations
- Bacterial Culture
- Viral Culture
- Blood Studies
- Dermatopathology
Course and Prognosis
- In many patients, the disease persists for 15–20 years, but is less severe. Thirty to fifty
percent of patients develop asthma and/or hay fever.
Management
- Baseline therapy of dryness with emollients
- Picture of management