Inflammatory dermatoses

Question 1

Describe the basic micro anatomy of the skin

Answer 1

3 layers:
Epidermis
Dermis
Subcutaneous tissue

Sweat glands, sebaceous glands, hair follicle and blood vessels found throughout

Question 2

Describe the structure of the stratum corneum

Answer 2

Very important for barrier function of the skin
Defects lead to eczema
Filagrin gene mutation common in eczema patients

Question 3

What is atopy and give examples of atopic diseases

Answer 3

Tendency to develop hypersensitivity

Eczema, asthma, hayfever

Question 4

What are the types of eczema

Answer 4

Atopic
Seborrhoeic
Allergic contact dermatitis
Discoid

Question 5

What are the intrinsic and extrinsic factors contributing to atopic eczema

Answer 5

intrinsic - leads to defects in epidermal skin barrier e.g. filagrin gene mutation

Extrinsic - Allergens (house-dust mite), irritants (detergents in soaps), pathogens (staphylococcus)

Question 6

Describe the immunology of atopic eczema

Answer 6

Activation of CD4+ lymphocytes and the Th2 immune response
Mast cell degranulation, releasing histamine

Chronic - Activation of CD4 and CD8 lymphocytes and Th1 immune response

Question 7

Describe the histology of psoriasis

Answer 7

Hyperkeratosis
Parakeratosis
Acanthosis
Inflammation
Dilated blood vessels

Question 8

Give examples of areas where psoriasis might manifest

Answer 8

Soles
Subungual hyperkeratosis (under nails)
Nails
Palms
Back (guttate)

Question 9

What is acne

Answer 9

Disease of the pilosebaceous unit of the skin

Question 10

Describe acne pathogenesis

Answer 10

1. Hyperkeratinisation of the epidermis in the infundibulum of the hair follicles
2. Accumulation of dead keratinocytes in hair follicle lumen
3. Increase sebum production stimulated by androgens
4. Proliferation of propionibacterium acnes within the pilosebaceous unit
5. Rupture of the inflamed pilosebaceous unit, with further inflammation of the surrounding skin

Question 11

What are some factors that lead to acne

Answer 11

Comedone formation
Genetic predisposition
Propionibacteria acnes
Androgenic stimulation

Question 12

What are the clinical features of acne

Answer 12

Whiteheads (closed comedones)
Blackheads (open comedones)
Papule
Nodules
Pustules

Question 13

What is bullous pemphigoid

Answer 13

An autoimmune bullous inflammatory condition most common in the elderly.

Question 14

Describe the pathology of bullous pemphigoid

Answer 14

IgG autoantibodies to basement membrane antigens BP180 (type XVII collagen) or BP230 result in cleavage of the skin at the dermo epidermal junction leading to sub epidermal blisters.

Question 15

What is a clinical sign of the filagrin gene mutation

Answer 15

Palmar hyperlinearity

Question 16

What is eczema

Answer 16

Very common itchy skin condition. Onset often within first 6 months of life. Many children will grow out of it, but a proportion does not.

Question 17

Describe the biology of eczema

Answer 17

Defective barrier function of the skin, leading to dry skin.
Filagrin gene mutations in 10% of cases.
Defective barrier function allows penetration of irritants, allergens (eg house dust mite particles) and pathogens eg staph aureus. Inflammation of the skin then occurs.

Question 18

What is filagrin

Answer 18

Filagrin is an epidermal protein important in maintaining barrier function of the skin.

Question 19

Describe seborrheic eczema

Answer 19

A very common type of eczema affecting babies and adults.
Often not itchy.
There is overgrowth of malassezia species of yeast on the skin with associated skin inflammation.
The rash has a distinctive distribution including nasolabial folds, eyebrows, scalp, central chest and sometimes axillae and groins.

Question 20

Describe the biology of psoriasis

Answer 20

Many genes are implicated including PSOR1
Immune process occurs where T lymphocytes move out of blood vessels into the dermis and initiate the release of cytokines, eg Tumour Necrosis Factor Alpha
The Epidermis becomes thickened and produces more keratinocytes than normal, neutrophils infiltrate the epidermis and lymphocytes infiltrate the dermis.

Question 21

Give examples of psoriasis triggers

Answer 21

Infections, drugs and stress.

Question 22

What are the clinical features of bullous pemphigoid

Answer 22

intense pruritus followed by the development of tense blisters on an erythematous background of skin or mucous membranes

Question 23

What is pemphigus vulgaris

Answer 23

An uncommon autoimmune bullous inflammatory disease, which usually affects middle aged individuals.

Question 24

What are the clinical features of pemphigus vulgaris

Answer 24

flaccid blisters which easily break leaving erosions and crusted lesions.

Question 25

Describe the biology of pemphigus vulgaris

Answer 25

IgG autoantibodies to epidermal cell surface proteins desmogleins 1 and 3 lead to loss of cell-cell adhesion (acantholysis) within the epidermis causing flaccid blisters in the skin or mucous membranes.