Rashes

Question 1

What is hyperkeratosis?

Answer 1

Increased thickness of the keratin layer

Question 2

What is parakeratosis?

Answer 2

Persistence of nuclei in the keratin layer

Question 3

What is acanthosis?

Answer 3

Increased thickness of the epithelium

Question 4

What is papillomatosis?

Answer 4

Irregular epithelial thickening

Question 5

What is spongiosis?

Answer 5

Intercellular oedema develops in the epidermis

Question 6

What are the 4 main reaction patterns of inflammatory skin diseases?

Answer 6

Spongiotic
Psoriasiform
Lichenoid (basal layer damage)
Vesiculobullous (blistering)

Question 7

What are examples of each reaction pattern of inflammatory skin disease?

Answer 7

Spongiotic - interaepidermal oedema
Psoriasiform - psoriasis
Lichenoid - lichen plan’s, SLE
Vesiculobullous - pemphigoid, pemphigus, dermatitis herpetiformis

Question 8

What is psoriasis?

Answer 8

A common chronic inflammatory dermatosis

Question 9

What is the pathology of psoriasis?

Answer 9

Unclear

Complement attracts neutrophils to the keratin layer

Question 10

What is the clinical presentation of psoriasis?

Answer 10

Symmetrical bilateral well-demarcated silvery or erythematous plaque
Nail changes - onycholysis, pitting, hyperkeratosis
Extensors, scalp, etc

Question 11

What is acute psoriasis?

Answer 11

Covering body
Underlying cutaneous lymphoma, drug reaction or psoriasis
Manage as if severe widespread burn

Question 12

What is the histological appearance of psoriasis?

Answer 12

Elongation of ridges, which become club-shaped and fuse with neighbouring ridges
Few lymphocytes in dermis
Neutrophil polymorphs
Abscesses

Question 13

What are lichenoid disorders?

Answer 13

Conditions characterised by damage to basal epidermis

Question 14

What is the most common lichenoid disorder?

Answer 14

Lichen planus

Question 15

What is the clinical presentation of lichenoid disorders?

Answer 15

Itchy flat-topped raised papules

Question 16

What is the histological appearance of lichenoid disorders?

Answer 16

Irregular sawtooth acanthuses (thickening of epidermis)
Hypergranulosis (thickened granular layer) and hyperkeratosis (thickened keratin later)
Infiltrate of lymphocytes
Basal damage with formation of cytoid bodies

Question 17

What is pemphigus?

Answer 17

A group of rare autoimmune bullous diseases
Loss of integrity of epidermal cell adhesion
All involve acantholysis
Intraepidermal

Question 18

What is acantholysis?

Answer 18

Lysis of intercellular adhesion sites

Question 19

What patients usually present with pemphigus?

Answer 19

Middle aged

Question 20

What is the treatment for pemphigus?

Answer 20

Steroids

Question 21

What is the most common variant of pemphigus?

Answer 21

Pemphigoid vulgaris

Question 22

What is the pathophysiology of pemphigoid vulgaris?

Answer 22

IgG auto-antibodies attack desmoglein 3, the protein that maintains desmosome attachments
Immune complexes form on cell surface and activates complement, causing protease release
Disruption of desmosomes causes acantholysis

Question 23

What is the clinical presentation of pemphigoid vulgaris?

Answer 23

Fluid filled blisters which rupture to form shallow erosions
Involves skin, especially scalp, face, axillae, groin, trunk
May affect mucosa

Question 24

How is diagnosis of pemphigoid vulgaris done?

Answer 24

Immunofluorescence - chickenwire pattern

Question 25

What is bullous pemphigoid?

Answer 25

Sub-epidermal blister | No acantholysis

Question 26

What is the pathophysiology of bullous pemphigoid?

Answer 26

IgG antibodies attack the hemidesmosomes anchoring basal cells to the basement membrane This causes local complement activation and tissue damage

Question 27

How is diagnosis done for bullous pemphigoid?

Answer 27

Immunofluorescence - linear pattern | Histology for early lesions

Question 28

What is dermatitis herpetiformis?

Answer 28

Rare autoimmune bullous disease | Associated with coeliac, 90% have gluten sensitive enteropathy

Question 29

What is the clinical presentation of dermatitis herpetiformis?

Answer 29

Intensely itchy symmetrical lesions Elbow, knees and buttocks Papollary dermal microabscesses

Question 30

What is the pathophysiology of dermatitis herpetiformis?

Answer 30

IgA antibodies target gliadin component of gluten and cross react with connective tissue matrix proteins Immune complexes form in dermal papillae and activate complement and generateneutrophil chemotaxins

Question 31

How is dermatitis herpetiformis diagnosed?

Answer 31

Immunofluorescence - granular IgA deposits in dermal papillae

Question 32

Where are the common sites for acne?

Answer 32

Sebaceous gland sites - face, upper back, anterior chest

Question 33

What is the aetiology of acne?

Answer 33

Androgens are released in puberty Sebaceous glands are sensitised to androgen Keratin plugging of pilosebaceous units Infection with anaerobic bacterium corynebacterium acnes

Question 34

What does keratin and sebum build up produce?

Answer 34

Comedones (black and whiteheads)

Question 35

How does rosacea present?

Answer 35

Recurrent facial flushing Visible blood vessels Pustules Thickening of the skin

Question 36

Who tends to get rosacea?

Answer 36

10% in caucasian adults Commoner in females Aged 30-60

Question 37

What are some factors that can trigger rosacea?

Answer 37

``` Sunlight Alcohol Spicy foods Stress Tetracyclines ```

Question 38

What is the pathology of rosacea?

Answer 38

Vascular ectasia Patchy inflammation with plasma cells Pustules Perifollicular granulomas

Question 39

What are risk factors for psoriasis?

Answer 39

15-25 y/os, 50-60 y/os Environmental factors - stress, drugs (beta blockers), previous infection Family history

Question 40

What are common comorbidities in psoriasis?

Answer 40

``` Psoriatic arthritis Metabolic syndrome Crohn's disease Cancer Depression Uveitis ```

Question 41

What is the management for psoriasis?

Answer 41

``` Emollients Vitamin D analogues Coal tar Dithranol Steroid ointments Phototherapy Immunosuppression ```

Question 42

What is the management for acne?

Answer 42

Benzoyl peroxide Vitamin A derivatives Antibiotics Isotretinoin

Question 43

What are the morphological features of acne?

Answer 43

Comedones (black and white heads) Pustules and papules Cysts Erythema

Question 44

What is the management for rosacea?

Answer 44

Reduce aggravating factors (dietary triggers, sun exposure, topical steroids) Metronidazole Oral tetracycline

Question 45

What is the management for lichenoid disorders?

Answer 45

Emollients Symptomatic treatment (steroids) Phototherapy

Question 46

What is the difference between bullous pemphigoid and pemphigus?

Answer 46

BP - split is deeper, through the derma-epidermal junction | P - split is more superficial, intra-epidermal

Question 47

What are the investigations for bullous pemphigoid and pemphigus?

Answer 47

Skin biopsy and immunofluorescence

Question 48

What is the management for bullous pemphigoid and pemphigus?

Answer 48

Systemic steroids Immunosuppression Emollients Tetracycline antibiotics in pemphigoid