Dermatology Basics

Question 1

What is a quick way of differentiating causes of purpura and petechiae?

Answer 1

• Purpura are petechiae >5mm
• Cough/vomit purpura occur in the SVC distribution and are typically non-palpable

Question 2

What is the classic Pentad of Thrombotic Thrombocytopaenic Purpura?

Answer 2

• Thrombocytopaenia
• Haemolytic anaemia
• Renal failure
• Fever
• Altered mental status

Haemolytic anaemia + thrombocytopaenia is enough to suspect TTP

Differentiated from DIC by having normal PT, PTT and fibrin levels

Treatment
- Plasmapharesis
- Platelet transfusion will not help and will cause more microthrombus formation

Question 3

What is Purpura Fulminans?

Answer 3

• an extreme, pro-thrombotic subtype of DIC
• Massive microvascular thrombosis causing multiorgan failure and large areas of purpuric bullae and skin necrosis
• usually caused by severe sepsis
• Can be autoimmune against protein S or innate errors or C/S

Question 4

What is a quick way of differentiating the causes of erythematous rashes?

Answer 4

• Erythema is caused by capillary congestion from vasodilation

Question 5

What is Nikolsky’s sign?

Answer 5

When skin sloughs with lateral pressure

Question 6

What is a quick way of differentiating Maculopapular rashes?

Answer 6

• Macules are non-palpable, Papules are palpable
• Meningococcaemia can manifest with a maculopapular rash before it develops the classic purpuric rash

Question 7

What is a quick way of differentiating Vesiculobullous rashes?

Answer 7

• Vesicles are <1cm, bullae >1cm
• SJS and TEN may also present with bullae although less common
• Nikolsky’s sign should also be used to help differentiate the cause

Question 8

What are the basics of Smallpox?

Answer 8

• Variola virus (DS DNA)
• Good potential for biological warfare (highly infectious, airborne)
• Unvaccinated mortality 30-50%
• High fever, headache, malaise, myalgias
• Widespread vesicular rash that involves the mucous membranes
• Differentiated from Varicella by all the lesions being at the same stage (varicella varying stages)

Question 9

What is the difference between Bullous pemphigoid (BP) and Pemphigus Vulgaris (PV)?

Answer 9

Nikolskys sign
- PV +ve, BP -ve

Age
- PV 40-60
- BP >65

Bullae type
- PV flaccid, superficial, coalesce
- BP Large and tense

Mucosal involvement
- BP uncommon (10-30%)
- PV always

Severity
- PV may require management in burns unit/ICU
- BP less severe but still may be bad

Question 10

How is Eczema Herpeticum typically described? What are the risks for severe disease and potential complications?

Answer 10

• Eythematous monomorphic blisters usually with areas of confluence
• Central punched out appearance
• They may weep or bleed
• Older lesions crust over and form sores/erosions

Question 11

What is the treatment of Eczema Herpeticum?

Answer 11

• If well, PO Aciclovir 10mg/kg 5 times a day for 7 days
• If unwell then IV Aciclovir 20mg/kg TDS if neonate, 10mg/kg TDS if older
• Analgeisa
• IV fluids if Septic
• Cover for secondary bacterial infection (ie Flucloxacillin 2gm QID)
• Urgent discussion with dermatology
• Cease any immunosuppressants

Question 12

What is the basic management of eczema?

Answer 12

General
- Daily bathing (lukewarm, capful of bathing oil, avoid soap/shampoo)
- Moisturiser top to toe twice a day
- Avoid overheating
- Avoid dry skin (eczema less prevalent in higher humidity)
- Avoid dribbling (ie from dummies), use peri-oral cream if needed
- Avoid irritants (nails short, dont scratch, avoid prickly fabrics, avoid perfumed detergent)
- Avoid skin infections

Flares
- Topical steroids under mosturiser
- Moisturisers QID
- Wet dressings TDS for 3 days
- Treat infections
- Bleach baths daily (+/- salt and oil to the bath)