Xerosis and Dermatitis 1 Flashcards
Xerosis (what is it? other name?)
AKA dry skin
- The skin is lacking moisture and this results in cracks in the skin surface.
- It is often characterized by a pattern of fine lines, scaling and itching
- Dry skin is commonly seen in people with atopic dermatitis (eczema).
Xerosis - Pathophysiology (4 GENERAL POINTS)
Dry skin due to abnormalities in the integrity of the barrier function of the stratum corneum
Too much involucrin (a protein) may be expressed early, increasing cell stiffness.
Impaired skin barrier = increase in transepidermal water loss (TEWL)
Immune Response
Xerosis - Pathophysiology-what are the contributing abnormalities (5)
Multiple contributing abnormalities:
1. There is an overall reduction in the lipids in the stratum corneum
2. Ratio of ceramides, cholesterol and free fatty acids may be altered.
- Most skin barrier disorders are characterized by a decreased ceramide content which leads to a defect in the epidermal layer.
3. Abnormal filaggrin (protein that bind to keratin fibers in the epidermal cells) expression
- This results in corneocyte deformation (flattening of surface skin cells), which disrupts the
organization of the extracellular lipid (fat).
4. There may be a reduction in proliferation of keratinocytes.
- Keratinocyte subtypes change in dry skin with decrease in keratins K1, K10 and increase in K5, K14.
5. too much involucrin (protein) may be expressed early, increasing cell stiffness
Xerosis - Risk & Aggravating Factors (4)
- Age and Disease - (Nearly everyone > 60 years has dry skin, Postmenopausal, Hypothyroidism, Malignancy, HIV, Chronic renal disease, Diabetes, Malnutrition and weight loss)
- Drugs - (Retinoids (oral especially), Diuretics)
- Environmental - (Low humidity: in desert climates or
cool, windy conditions, Excessive air conditioning, Direct heat from a fire or fan heater, Excessive bathing, Contact with soap, detergents and solvents, Inappropriate topical agents such as alcohol, Frictional irritation from rough clothing or abrasives) - Genetics -(There is often a family history of dry
skin, Those with atopic dermatitis are more
susceptible )
Xerosis - Presentation
Xerosis presents as: - dull surface - rough - scaly - cracked When the skin becomes inflamed and fissured, it is classified as dermatitis
Dermatitis (what is it? other name?)
AKA “skin-inflammation”
-Non-specific term that describes a skin reaction that exhibits
swelling, erythema, scaling, vesicles and/or crusts.
-This term refers to a group of inflammatory conditions that affect the epidermis layer
Dermatitis - Inflammatory response acute vs chronic
Acute: refers to a rapidly evolving red rash which may be blistered and swollen
Chronic: refers to a longstanding irritable area. It is often darker than the surrounding skin, thickened (lichenified) and `s evident of scratching.
What is the Immune response for dermatitis? (think of the skin diagram)
- Immune activation by resident innate immune cells leads to type 2 inflammation, led by inflammatory cytokines IL-4, IL-13, and IL-31.
- Type 2 inflammation mediates barrier disruption, promotes further inflammation, and increases itch, leading to acute skin lesions.
- Chronic disease is characterized by intensification of the effect of type 2/Th2 cytokines as well as involvement of Th1 inflammation, resulting in lichenification of the skin
- Innate immune cells and proteins are always present and read to mobilize to fight microbes
- Th1 and Th2 is off balance
Dermatitis - Presentation - Acute
- Erythema due to dilatation of the small blood vessels
- Edema due to leakage of fluid from blood vessels and accumulation in tissues (vesicles may form).
- Breakage of blisters results in oozing or weeping (vesicles), and evaporation of this fluid
causes crusting and scaling. - Itchy
Dermatitis - Presentation - Chronic
- Skin becomes dry, and cracked (fissures). With
prolonged itching and scratching, it thickens and the
normal skin markings become more prominent (lichenfication). - Scaling and hyperpigmentation may be present
- Itchy
Atopic Dermatitis (what is it? other name?)
AKA - Eczema “to boil over”
Can be acute or chronic
Atopic Dermatitis Epidemiology
- Onset typically occurs early in life, with 60% of cases presenting by 1 year and 90% presenting by 5 years of age.
- Prevalence of AD in the adult population varies regionally but is estimated to be up to ~10%.
- Most cases of pediatric AD do resolve, a significant proportion do not, and in fact a small percentage of patients may first develop symptoms in adulthood.
Atopic Dermatitis - Pathophysiology and Contributing Factors
- Pathophysiology of AD is complex and includes genetic, immune, and environmental factors contributing to chronic inflammation.
Atopic dermatitis, allergic rhinitis/conjunctivitis and allergic bronchial asthma belong to the atopic syndrome, or atopic diathesis (atopic triad) - Impaired barrier function makes skin more susceptible to environment and external triggers leading to exaggerated immune response
Atopic Dermatitis - Presentation
locations?
3 phases of AD:
Infantile (<2yr): scalp, cheeks, outer elbows, middle chest, knees, diaper area
Childhood (2yr-puberty): neck, inner elbows, behind knees, feet
Adult: hands and feet
there is mild, moderate and severe AD
Start prescription therapy if there is morbidity
Secondary skin infections - AD
- Skin microflora
Frequently (and more correctly) called the skin microbiota or the skin microbiome
i.e. microorganisms that are resident on our skin - Total microbial cell count in and on our bodies is similar to the number of human cells
After the gut, there are more microorganisms on the
skin than anywhere else in the body
Majority are bacterial species; however fungi, viruses and mites are also found on the skin of normal healthy humans - The majority of microorganisms on our skin are commensals, as they infrequently cause ill health.
Commensal microorganisms can prevent colonization of pathogenic microorganisms such as S. aureus - However, in some circumstances commensal microbes such as S. epidermidis have beneficial or pathogenic roles.
- There are products on the market that affect the microbiome in a good way
