Disease of the Skin

Question 1

Immunological reaction is activated by

Answer 1

The Langerhans cells, part of the innate immune system (in the epidermis) able to recognize allergens or hapten.

Question 2

Hapten is

Answer 2

a small molecule able to penetrate through the keratinocyte layer and combine with structural protein in the skin to form a complete allergen.

Question 3

Atopic Dermatitis/Atopy is

Answer 3

• an Hypersensitivity Type 1 reaction (involve IgE antibodies, mast cells releasing histamine)
• Allergic reaction and multifactorial disease (genetic, environmental, IgE mechanism, epidermal barrier dysfunction)
• Cause damage to the epidermal barrier
• The tight junctions and filaments between the keratinocytes in the epidermis are no longer present, which fagilize the skin surface and allows allergen to penetrate the skin.

Question 4

Dermatitis Herpetiforms is

Answer 4

• an Immune Complex Deposition, maintly IgA
• related to Celiac’s disease
• There is a component called TG that is commonly found in the intestine –> IgA produced against the TG –> IgA circulating will recognize a similar component in the skin and form immune complex deposit in the dermal-epidermal region releasing neutrophil and chemotactic factors.

Question 5

Irritant Contact Dermatitis:

Answer 5

• Most common type of Dermatitis
• occurs when skin comes into contact with an irritant (eg. solvent, soap, baisc or acidic product)
• Damage the epithelial barrier with the keratinocytes and triggers inflammation

Question 6

Allergic Contact Dermatitis:

Answer 6

-Due to contact with an allergen (eg. poison oak or poison ivy, nickel)

Question 7

Psoriasis:

Answer 7

• 90% are of P. Vulgaris type.
• associated with arthritis (25% have arthritis)
• Female and male equal risk
• Thickening of the stratum corneum, increase blood flow to the dermis with angiogenesis and inflammation (IL-17).
• Extensive proliferation of keratinoytes (abnormal composition–> squamous keratinocytes attached by filaments and fast turnover)

Question 8

Stratum lucidem and Stratum corneum are:

Answer 8

Dead Cells.

Question 9

Therapy of Psoriasis mechanisms:

Answer 9

Blocking IL-17 gives rapid reversal in over 80% of people.

Question 10

Acne:

Answer 10

• Hyperseborrhea with pro-inflammatory lipids
• Inflammation (increase with sebum blocking the duct)
• Propionibacterium acnes grows (when excess sebum+duct blocked)
• Epithelial proliferation (block the duct)

Question 11

UV Radiation Damage:

Answer 11

• UV light cause the skin to express RANKL and Langerhans cells which promote T-regulatory cells (to suppress the immune system)
• RNA is released from keratinocytes after UVB exposure and stimulates the inflammatory cytokines TNF alpha and IL-6.

Question 12

Skin Cancer:

Answer 12

• 3 majors types: Basal cell carcinoma–> responsible for the formation of new cells (most common in Canada), Squamous cells (keratinocytes) and the Melanoma (melanocytes)
• UV light causes changes in the chemical carcinogenesis in the skin

Question 13

Melanoma:

Answer 13

-the cells begins to multiplying and extending into the basal layer of the epidermis and eventually breaking through the dermis, gaining access to the circulation
Solar Lentigo: spot not malignat but need to be monitored

Question 14

Dermatophytoses:

Answer 14

-Fungal infection (Athlete’s Foot)

Question 15

Warts:

Answer 15

• Cause by HPV
• Epidermal hyperplasia
• Cytoplasmic vacuoles (koliocytosis)