Dermatology

Question 1

What is Urticaria?

Answer 1

• Definition: Urticaria, or hives, is an erythematous, blanching, itchy skin swelling that appears quickly (within minutes) and typically resolves in under 24 hours without skin marks.
• Common Causes: Most often allergy-related; can also have non-allergic triggers.
• Angioedema: Present in ~40% of cases, involving deeper swelling, often affecting the face, lips, and airways, lasting up to 72 hours and may be painful rather than itchy.
• Types:
  • Acute: <6 weeks, often stimulus-triggered and self-limiting.
  • Chronic: ≥6 weeks, typically without a specific trigger.

Question 2

H&E for Urticaria

Answer 2

• Pale, pink raised skin
  
  • Described as ‘hives’, ‘wheals’, ‘nettle rash’
• Pruritis
• Resolution with 24 hours

Other diagnostics:
- Blanching lesions

Question 3

RF for Urticaria

Answer 3

Recent exposure to drug/food trigger, viral infection or insect bite/sting

Drugs that commonly cause urticaria:
- aspirin
- penicillins
- NSAIDs
- opiates

Question 4

Investigations for Urticaria

Answer 4

Bloods:
- FBC, ESR, CRP

Question 5

Management of Urticaria

Answer 5

• Non-sedating antihistamines
• Prednisolone for sever or resistant episodes

Question 6

What are Arterial Ulcers?

Answer 6

Often the result of damage to the arteries due to poor circulation and blood flow

Blood unable to flow into lower extremities like legs and feet

When skin and underlying tissue deprived of oxygen, tissue starts to die off and form an open wound

Question 7

H&E of Arterial Ulcers

Answer 7

• Punched out appearance
• Typically circular with red, yellow or black colouration
• Well defined edges
• On toes and heels
• Pain
• Cold with no palpable pulses
• Could be gangrenous

Question 8

Investigations for Arterial Ulcers

Answer 8

ABPI - will be low

Question 9

Management of Arterial Ulcers

Answer 9

• Keeping wound dry
• Lifestyle changes
• Orthopaedic shoes
• Angioplasty to restore blood flow

Question 10

What are Pressure Sores?

Answer 10

Defined as localised damage to the skin and underlying soft tissue usually over bony prominence or related to medical or other device

Can be intact or open ulcer due to prolonged pressure

Question 11

H&E of Pressure Sores

Answer 11

• Use of non-pressure-relieving support surface
• Localised skin changes on areas with pressure
• Localised tenderness and warmth around wound
• Increased exudate and/or foul odour

Question 12

RF of Pressure Sores

Answer 12

• Immobility
• Sensory impairment
• Older age
• Surgery
• Malnourishment

Question 13

Investigations for Pressure Sores

Answer 13

Clinical diagnosis

OTHER

• Wound swab if signs of infection
• ESR and WBC to rule out osteomyelitis
• Serum glucose to exclude diabetes

Question 14

Management of Pressure Sores

Answer 14

• Pressure-reducing aids and repositioning
• Hygiene and cleansing + dressings
• Analgesia
• Dietary optimisation
• Abx if required
• Debridement if deep ulcer with necrotic tissue

Question 15

Pathophysiology of Psoriasis

Answer 15

Multifactorial and not yet fully understood

Associated HLA- B13, -B17 and -Cw6, strong concordance (70%) in identical twins

Abnormal T cell activity stimulates keratinocyte proliferation
May be mediated by novel group of T helper cells producing IL-17

Question 16

Environmental factor affecting Psoriasis

Answer 16

May be worsened e.g. skin trauma, stress

Triggered e.g. streptococcal infection

Improved e.g. Sunlight

Question 17

Recognised subtypes of Psoriasis

Answer 17

Plaque : MC type - typical well-demarcated red, scaly patches affecting extensor surfaces, sacrum and scalp

Flexural : in contrast to plaque, the skin is smooth

Guttate : transient rash frequently triggered by strep infection - multiple red, teardrop lesions appear on body

Pustular : commonly occurs on the palms and soles

Question 18

H&E of Psoriasis

Answer 18

Key : skin lesions

Other :
- joint swelling or pain (psoriatic arthritis)
- nail signs (pitting, onycholysis)

Question 19

Risk Factors for Psoriasis

Answer 19

-FHx
- Infection
- Local trauma
- Medications

Question 20

Investigations for Psoriasis

Answer 20

Clinical diagnosis

Consider Skin biopsy

Question 21

Management of Psoriasis

Answer 21

• Topical therapies if mild

For chronic plaque :
- Potent corticosteroid + separate vit D analogue
- If no improvement after 8 weeks - vit D analogue BD
- If no improvement after 8-12 weeks - corticosteroids BD or coal tar preparation

For scalp :
- Potent topical corticosteroid

For face, flexural and genital :
- Mild/ moderate corticosteroid

Question 22

What is Cellulitis?

Answer 22

A term used to describe an inflammation of the skin and subcutaneous tissue, typically due to infection by Strep. pyogenes or Staph. aureus

Question 23

H&E of Cellulitis

Answer 23

• Erythema, normally well-defined
• Pain
• Swelling
• Commonly on shins and unilateral
• Systemic symptoms e.g. fever

Question 24

RF for Cellulitis

Answer 24

• DM
• Venous insufficiency
• Eczema
• Previous episodes

Question 25

Investigations for Cellulitis

Answer 25

Clinical diagnosis Consider FBC, CRP, ESR, U&Es and blood cultures if septic

Question 26

Eron Classification for Cellulitis

Answer 26

I - no signs of systemic toxicity + person has no uncontrolled co-morbidities II - Systemically unwell/ well but with a co-morbidity which may complicate or delay resolution of infection III - Significant systemic upset such as acute confusion, tachycardia, tachypnoea, hypotension or unstable co-morbidities that may interfere with a response to treatment or a limb-threatening infection due to vascular compromise IV - Sepsis syndrome or severe life-threatening infection such as necrotising fasciitis

Question 27

Reasons to admit patient for Abx for Cellulitis

Answer 27

- Eron Class III or IV - Severe or rapidly deteriorating cellulitis - Very young (under 1 yo) or frail - Immunocompromised - Has significant lymphoedema - Facial cellulitis or periorbital cellulitis

Question 28

Management of Cellulitis

Answer 28

- Oral flucloxacillin - If allergic to penicillin - clarithromycin, erythromycin (in pregnancy) or doxycycline - For severe cellulitis - IV co-amoxiclav, cefuroxime, clindamycin or ceftriaxone

Question 29

What is Atopic Dermatitis and Eczema?

Answer 29

- Inflammatory skin condition - Characterised by dry, pruritic skin with chronic relapsing course - MC diagnosed before 5yo and affects 10-20% of children

Question 30

H&E of Atopic Dermatitis and Eczema

Answer 30

Key: - Pruritis - Xerosis (dry skin) Other: - Erythema - Scaling - Vesicles + papules - Excoriations - Lichenificaiton - Hypopygmentation

Question 31

RF for Atopic Dermatitis and Eczema

Answer 31

- Filaggrin gene loss-of-function mutation - Age <5 - FHx - Allergic rhinitis - Asthma

Question 32

Investigations for Atopic Dermatitis and Eczema

Answer 32

Clinical diagnosis Patch testing if dermatitis is difficult to control or external trigger suggested

Question 33

Management of Atopic Dermatitis and Eczema

Answer 33

Emollients Consider topical steroids and Abx if severe

Question 34

What is Necrotising Fasciitis?

Answer 34

Medical emergency that is difficult to recognise in the early stages

Question 35

Classification of Necrotising Fasciitis

Answer 35

Type 1 : caused by mixed anaerobes and aerobes (often post-surgery in diabetics) MC form Type 2 : caused by Strep. pyogenes

Question 36

RF of Necrotising Fasciitis

Answer 36

Skin factors : recent trauma, burns or soft tissue infections DM : MC preexisiting medical condition IVDU Immunosuppression MC affected site is perineum (Fournier’s gangrene)

Question 37

H&E of Necrotising Fasciitis

Answer 37

Acute onset Pain, swelling, erythema at the affected site - often presents as rapidly worsening cellulitis with pain out of keeping with physical features - extremely tender over infected tissue with hypoaesthesia to light touch - skin necrosis and crepitus/gas gangrene are late signs Fever and tachycardia may be absent or occur late in the presentation

Question 38

Management of Necrotising Fasciitis

Answer 38

- Urgent surgical debridement - IV Abx : penicillin, aminoglycoside, clindamycin Average mortality 20%

Question 39

How does virus cause Exanthem rash?

Answer 39

1. Rash is body’s immune response to the virus 2. Damage to your skin by the organism 3. Reaction to toxin the virus produces

Question 40

Viruses that cause Exanthem rash

Answer 40

Chicken pox (varicella-roster) COVID-19 Fifth disease (parvovirus B19) Hand, foot and mouth disease (coxsackievirus A16) Measles Roseola Rubella

Question 41

H&E of Viral Exanthema

Answer 41

Other viral symptoms

Question 42

Management of Viral Exanthema

Answer 42

- Isolation - Self-limiting - Analgesics, NSAIDs