Inflammatory Dermatoses

Question 1

What broad categories is the skin divided into?

Answer 1

Epidermis
Dermis
Hypodermis

Question 2

Describe more in depth the structure and layout of the epidermis

Answer 2

From superficial to deep
Stratum corneum
Stratum lucidum
Stratum granulosum
Stratum spinousum
Stratum basale

(then dermis)

Question 3

State the cells of significance found in the Stratum corneum,

Answer 3

Stratum corneum- dead keratinocytes, those on surface flake off
Stratum granulosum- lameller granules
Stratum spinousum- 95% living keratinocytes, also langerhans (immune) cells
Stratum basale- Merkel cells (touch receptors), melanocytes, keratinocyte stem cells

Question 4

Describe the keratinocyte differentiation pathway

Answer 4

basal cell
prickle cell
granular cell
keratin

Question 5

Describe the structure and function of the stratum corneum

Answer 5

Most superficial layer of epidermis
Very important for barrier function of skin
Composed of corneocytes (differentiated keratinocytes) with lipids between them

Question 6

What condition does a defect in the stratum corneum lead to?

Answer 6

Eczema

Question 7

What does atopy mean?

Answer 7

tendency to develop hypersensitivity such as in allergic rhinitis, asthma and atopic dermatitis (eczema), hay fever

Question 8

What are the four types of Eczema?

Answer 8

Atopic
Seborrheic
Discoid
Allergic contact dermatitis

Question 9

Describe atopic eczema and its cause.

Answer 9

Itchy skin, presents in first 6 months of life (many grow out of it)
Caused by defective barrier of skin, 10% os patients have gene mutation in Filagrin (palmar hyper-linearity)
Defective barrier allows entry of irritants, allergens and pathogens which cause inflammation

Question 10

What is palmar hyper linearity

Answer 10

Sign of gene mutation in the epidermal protein Filagrin

Question 11

Where are infants commonly affected by atopic eczema/dermatitis?

Answer 11

Face
Knees
Elbows

Question 12

Describe seborrhoeic eczema and its cause

Answer 12

Affects adults and babies but NOT itchy

Associated with overgrowth of MALASSEZIA species of yeast on the skin that causes inflammation

Question 13

Describe the distribution of the rash seen in Seborrheic eczema

Answer 13

Nasolabial folds
Eyebrows
SCALP
Central chest
Axilla
Groin

Question 14

What is distinctive about discoid eczema?

Answer 14

Occurs in small discrete discs

Question 15

When does psoriasis typically present?

Answer 15

Adulthood
Tenns or 40/50s
formation of inflamed, raised plaques

Question 16

What percentage of people with psoriasis have psoriatic arthritis?

Answer 16

30%

Question 17

What are the four main types of Psoriasis?

Answer 17

Chronic plaque
Guttate
Palmoplantar pustulosis
Generalised pustular psoriasis

Question 18

What gene is particularly implicated in Psoriasis?

Answer 18

PSOR1

and many others

Question 19

What features would you see on a slide of someone with Psoriasis?

Answer 19

Hyperkeratosis (thickening of the stratum corneum)
Parakeratosis (retention of nuclei in the stratum corneum- normal in mucous membranes not here)
Acanthosis (thickening of the skin)
Inflammation
Dilated blood vessels

Question 20

What is the pathophysiology of Psoriasis?

Answer 20

abnormally excessive and rapid growth of the epidermal layer of the skin.

T-lymphocytes move out of blood vessels into dermis and initiate release of cytokines (e.g TNFa)
Epidermis thickens in response (produces more keratinocytes)
Neutrophils infiltrate the epidermis
Lymphocytes infiltrate the dermis

Question 21

Who is mainly affected by acne?

Answer 21

Teenagers and young adults

Question 22

What is the pathophysiology of acne?

Answer 22

Hyperkeratinisation of epidermis
Accumulation of dead keratinocytes in lumen of hair follicle
Increased sebum production stimulated by androgens
Proliferation of bacteria within pilosebaceous unit
Rupture of hair follicle, further inflammation of surrounding skin

Question 23

What bacteria are responsible for acne?

Answer 23

Propionibacterium

Question 24

What are the clinical features of acne?

Answer 24

Open comedones- blackheads
Closed comedones- whiteheads 
Papules
Pustules
Nodules

Question 25

What factors are relevant to acne?

Answer 25

Comedone formation Genetic predisposition Propionibacterium Androgenic stimulation

Question 26

What is Bullous Pemphigoid?

Answer 26

autoimmune bullous (blister) inflammatory condition

Question 27

Who is most commonly affected by bullous pemphigoid?

Answer 27

Elderly

Question 28

What type of hypersensitivity reaction is bulbous pemphigoid?

Answer 28

type 2 hypersensitivity

Question 29

What are the clinical feature of bullous pemphigoid?

Answer 29

pruritus (itchy skin) followed by development of TENSE blisters on reddened skin

Question 30

What is the pathogenesis of bullous pemphigoid?

Answer 30

IgG auto antibodies against basement membrane antigens BP180 (aka collagen type 17) and BP230 result in cleavage of the skin at the DERMO-EPIDERMAL junction (basement membrane zone) leading to sub-epidermal blisters

Question 31

what is pemphigus vulgaris?

Answer 31

uncommon autoimmune bullous inflammatory disease

Question 32

Who is pemphigus vulgaris most common in?

Answer 32

Middle aged people

Question 33

What type of hypersensitivity reaction is pemphigus vulgaris?

Answer 33

type 2 hypersensitivity

Question 34

What are the clinical features of pemphigus vulgaris?

Answer 34

FLACCID blisters which break easily leaving erosions and crusted skin flaccid blisters seen in intra-epidermal diseases as seen here

Question 35

What is the pathogenesis of pemphigus vulgaris?

Answer 35

IgG auto antibodies to epidermal cell surface proteins (desmogleins 1/3) loss of cell-cell adhesion (acantholysis) within the epidermis causing flaccid blisters in skin or mucous membranes

Question 36

What are the similarities between BP and PV?

Answer 36

both autoimmune dieases both type 2 hypersensitivity both involve IgG auto antibodies both involve the formation of blisters (albeit different types)

Question 37

What are the differences between BP and PV?

Answer 37

BP more common that PV BP occurs in the elderly, whilst PV in the middle aged BP involves formation of tense blisters, flaccid blisters in PV BP occurs at dermo-epidermal junction whilst PV is intra-epidermal

Question 38

What is Nikolsky's sign and how can it be used to differentiate between BP and PV?

Answer 38

The sign is present when slight rubbing of the skin results in exfoliation of the outermost layer. Present in PV Absent in BP