Contact Dermatitis and Psoriasis

Question 1

Major commonality between contact dermatitis and psoriasis

Answer 1

Both T cell mediated!

Question 2

Phases of contact dermatitis

Answer 2

• Sensitization (10-15 day duration)
• Elicitation (stimulated by rechallenge)

Question 3

Answer 3

Spongiotic inflammation

Characteristic of contact dermatitis

Question 4

Allergic Contact Dermatitis

Answer 4

An adverse cutaneous inflammatory reaction caused by contact with a specific exogenous allergen to which a person has developed allergic sensitization. Comprise 20% of all contact dermatitis.

Question 5

Irritant Contact Dermatitis

Answer 5

An adverse cutaneous inflammatory reaction that occurs without sensitization, in direct proportion to the quantity/concentration and amount of exposure to the irritant exposure. Comprise 80% of all contact dermatitis.

Question 6

Classic presentation of allergic contact dermatitis

Answer 6

pruritic, eczematous dermatitis initially localized to the primary site of allergen exposure

Question 7

urushiol

Answer 7

Sensitizing substance for contact dermatitis in plants (like poison ivy). Released when plants are burned. Leads to more severe eruption on large swaths of body.

Question 8

Subacute to chronic allergic contact dermatitis presentation

Answer 8

• erythema
• scaly juicy papules
• fissuring
• lichenification
• pruritis
• may present as a line or streak suggestive of physical contact

Question 9

Important allergen classes in contact dermatitis

Answer 9

• Metals
• Topical medications
• Fragrances/dyes
• Preservatives
• Plants

Question 10

The most commonly diagnosed cause of allergic contact dermatitis

Answer 10

Nickel

Question 11

History taking for acute contact dermatitis

Answer 11

• Detailed history of usage of personal care products
• Investigation of hobbies, especially hiking
• Investigation of occupation (those requiring frequent hand washing, glove use, or frequent chemical exposure are most suspicious)

Question 12

Clinical pearls for contact dermatitis

Answer 12

• Should be suspected in any eczematous-appearing eruption
• Not always bilateral even when antigen exposure is bilateral
• Even when contact is uniform, lesions are often patchy
• Can and does affect palms and soles (while many dermatitis-causing diseases do not)
• Distribution of lesions on skin may give a clue to how it came into contact with the offending substance

Question 13

The gold standard for the diagnosis of allergic contact dermatitis

Answer 13

patch testing!!!

Question 14

Treatment of allergic contact dermatitis

Answer 14

• Strategy for avoiding antigen, usually involving substitution of items or behaviors
• Topical corticosteroids first line treatment for short-term (Corticosteroid allergy
  should be considered when an eruption persists, changes, spreads, or worsens following the use of steroids)
• topical calcineurin inhibitors (tacrolimus, etc)
• For severe ACD, courses of oral corticosteroids are often given with a slow taper

Question 15

Psoriasis is a prototypic ___-mediated autoimmune inflammatory skin disease

Answer 15

Psoriasis is a prototypic T resident memory cell-mediated autoimmune inflammatory skin disease

Question 16

Main cytokine driver of psoriasis

Answer 16

IL-17

Question 17

Under baseline conditions, ___ live next to___ in the skin that probably express the autoantigen they are specific for.

Answer 17

Under baseline conditions, resident autoreactive T cells live next to antigen presenting cells in the skin that probably express the autoantigen they are specific for.

Question 18

Psoriatic skin lesions become induced when damage to the skin, infection or any other stimulus that leads to . . .

Answer 18

Psoriatic skin lesions become induced when damage to the skin, infection or any other stimulus that leads to dendritic cell activation, up regulates costimulatory molecules on antigen presenting cells and this causes the proliferation of autoreactive T cells in the skin.

Question 19

Psoriatic inflammation

Answer 19

Question 20

Psoriatic lesions on H and E

Answer 20

• hyperkeratotic and parakeratotic scale of the startum corneum
• elongation of the rete ridges of the epidermis with focal neutrophilic collections
• thinning of the suprapapillary epidermis
• dilated superficial dermal blood vessels (from angiogenic factors)

Question 21

Psoriasis epidemiology

Answer 21

• 2% of individuals in US
• No anatomical sex preference
• Appears >30 years of age, often in teen years
• HLA-Cw6 haplotype associated with early onset and family history

Question 22

__% of psoriatic individuals go on to develop psoriatic arthritis

Answer 22

30% of psoriatic individuals go on to develop psoriatic arthritis

Question 23

rates of ___ and ___ are dramatically lower in individuals with psoriasis

Answer 23

rates of atopic dermatitis and allergic contact dermatitis are dramatically lower in individuals with psoriasis

Question 24

Clinical description of psoriasis

Answer 24

• Lesions are well-demarkated, erythematous-pinkish, raised plaques with a white-silver scaly surface
• Vary in size from pinpoint papules to plaques covering broad swaths of body
• bleeding points appear when the scale is removed, traumatizing the dilated capillaries below (the Auspitz sign)
• Symmetric eruption (typically)
  *

Question 25

Answer 25

Classic presentation of psoriatic arthritis

Question 26

Psoriasis vulgaris

Answer 26

Most common form (~90% of patients). Red, scaly, symmetrically distributed plaques characteristically localized to the extensor aspects of the extremities, particularly the elbows and knees, along with scalp, lower lumbosacral, buttocks, genitals, umbilicus and gluteal cleft. Single small lesions may become confluent, forming plaques in which the borders resemble a land map – “geographic” appearance.

Question 27

Inverse psoriasis

Answer 27

Psoriasis lesions may be localized in the major skin folds, such as the axillae, the genito-crural region, and the neck. Scaling is usually minimal or absent, and the lesions show a glossy sharply demarcated erythema

Question 28

Pustular psoriasis

Answer 28

usually preceded by other forms of the disease. Attacks are characterized by fever that lasts several days and a sudden generalized eruption of sterile pustules 2–3 mm in diameter. The pustules are disseminated over the trunk and extremities, including the nail beds, palms, and soles.

Question 29

Erythrodermic psoriasis

Answer 29

Psoriatic erythroderma represents the generalized form of the disease that affects all body sites. Although all the symptoms of psoriasis are present, erythema is the most prominent feature, and scaling is different compared with chronic stationary psoriasis. Instead of thick, adherent, white scale there is superficial scaling. Patients with erythrodermic psoriasis lose excessive heat because of generalized vasodilatation, and this may cause hypothermia as well as electrolyte disturbances and rarely high-output cardiac failure.

Question 30

Guttate psoriasis

Answer 30

characterized by eruption of small (0.5–1.5 cm in diameter) papules over the upper trunk and proximal extremities. Typically manifests at an early age, frequently in young adults.

Question 31

Treatment of psoriasis

Answer 31

• Most cases treated topically
• Ointment formulations, topical glucocorticoids, improvement in 2-4 weeks followed by lower-dose maintenance treatment
• Vitamin D3 analogs like calcipotriene or anti-inflammatories like topical calcineurin inhibitors also effective
• Phototherapy using UVA and UVB light is also effective (mechanism seems to be apoptosis of T_RM following a bout of Th2 inflammation in response to light)
• For severe cases, systemic corticosteroids, cyclosporine, retinoids, and anti-TNF/IL-17A/IL-22/IL-23 also useful

Question 32

___ is a potentially life-threatening form of psoriasis, and any other form of psoriasis may progress to it.

Answer 32

Erythroderma is a potentially life-threatening form of psoriasis, and any other form of psoriasis may progress to it.

Question 33

Answer 33

Psoriatic pitting of the nail

Question 34

Answer 34

Yellow/brown psoriatic discoloration of nail

Question 35

The onset of psoriasis in children often occurs as ___.

Answer 35

The onset of psoriasis in children often occurs as guttate psoriasis.

Question 36

Answer 36

Guttate psoriasis

Question 37

___ may follow a streptococcal infection of the upper resipiratory tract.

Answer 37

Guttate psoriasis may follow a streptococcal infection of the upper resipiratory tract.

Antigenic similarities between streptococcal proteins and keratinocyte antigens might explain the trigger

Question 38

Psoriatic skin diagram (highlighting important characteristics)

Answer 38

Question 39

Why is there so much keratinocyte proliferation in psoriasis?

Answer 39

IL-17 and IL-22 are keratinocyte growth factors!

Question 40

Type I psoriasis

Answer 40

Earlier onset, more severe

Question 41

Type II psoriasis

Answer 41

Later onset, milder form

Question 42

Psoriatic endothelial dysfunction

Answer 42

Chronic systemic inflammation induced by psoriasis leads to insulin resistance in endothelial cells, which results in a reduction of NOS activity and thus vasoconstriction. Adhesion molecules are also chronically upregulated. Both of these provide an environment which favors the development of atherosclerosis.

Question 43

Main type of T cell implicated in allergic contact dermatitis

Answer 43

T helper 1

So. . . yeah. . . Not so allergic after all

Question 44

A common trigger for contact dermatitis in fragrances and soaps

Answer 44

Balsam of Peru

Question 45

Koebner phenomenon

Answer 45

The traumatic induction of psoriasis on nonlesional skin; it occurs more frequently during flares of disease. The Koebner phenomenon is not specific for psoriasis but can be helpful in making the diagnosis when present.