Bullous disease Flashcards

1
Q

What are the 3 main autoimmune bullous skin diseases?

A
  1. Bullous phemphigoid
  2. Pemphigus
  3. Dermatitis herpetiformis (DH)
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2
Q

Define what bullous phemphigoid is

A

It is an autoimmune condition causing subepidermal blistering of the skin

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3
Q

Describe the pathogenesis of bullous phemphigoid

A
  • IgG antibodies react against hemidesmosomal proteins BP180 & BP230. These proteins are associated with hemidesmosomes which are structures responsible for anchoring basal cells to the basement membrane
  • Resultant local complement activation & tissue damage ensues leading to the development of a subepidermal blister
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4
Q

Who is mainly affected by bullous phemphigoid ?

A
  • Often presents in people > 60
  • Uncommon in younger people
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5
Q

Describe the distribution of bullous phemphigoid

A
  • It is usually widespread on the trunk & limbs, but in 15-30% it may be localised.
  • Uncommonly mucosal lesions may be present - most commonly the mouth (mouth usually spared tho)
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6
Q

What are the clinical features of bullous phemphigoid ?

A
  • Itchy erythematous plaques & papules may be presenting feature (pre-bullous development)
  • Severly itchy, tense fluid-filled blisters typically around the flexures
  • Blisters rupture forming crusted erosions
  • Blisters heal without scarring
  • Blisters are Nikolsky sign negative
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7
Q

What is shown in this pic ?

A

bullous phemphigoid - shows large tense bullae

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8
Q

What is Nikolsky sign?

A

This is dislodgement of the superficial epidermis by a shearing force

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9
Q

How is bullous phemphigoid diagnosed ?

A

1st line = skin biopsy + direct immunofluoresence (DIF)

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10
Q

What is the immunofluoresence appearance of bullous phemphigoid ?

A

Shows IgG & C3 at the dermoepidermal junction (green line in pic)

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11
Q

What is the treatment of localised bullous phemphigoid ?

A

Topical corticosteroids (ultra-potent e.g. Clobetasol propinate)

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12
Q

What is the treatment of generalised bullous phemphigoid ?

A

Oral steroids (prednisolone) + methotrexate + antibiotics (tetracycline - mainly doxycyline + dapsone)

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13
Q

What is the prognosis of bullous phemphigoid ?

A

Most patients achieve remission within 3-6months

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14
Q

What is the main type of pemphigus accounting for 80% of cases ?

A

Pemphigus vulgaris

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15
Q

What is pemphigus vulgaris ?

A

It is a rare autoimmune disease that is characterised by painful blisters & erosions on the skin & mucous membranes - most commonly inside the mouth

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16
Q

Who is usually affected by pemphigus vulgaris ?

A

Usually affects middle aged people (30-60) & most common in Ashkenazi jewish populations

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17
Q

Describe the distribution of pemphigus vulgaris

A
  • Most commonly arise on upper chest, back, scalp & face (axillae & groin)
  • 80% will have oral mucosal lesions & erosions (may also have erosions of vulvula, conjunctivae, pharynx, larynx, oesophagus & rectum)
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18
Q

Describe the pathogenesis of pemphigus vulgaris

A

Keratinocytes are cemented together at sticky spots called desmosomes. In pemphigus vulgaris IgG antibodies are directed against a protein called desmoglein 3 found in desmosomes. This results in acantholysis & the formation of intra-epidermal fluid-filled blisters

19
Q

Define what acantholysis is

A

Acantholysis = breakdown of intracellular adhesion sites, such as desmosomes resulting in loss of connection between keratinocytes

20
Q

What are the clinical features of pemphigus vulgaris ?

A
  • Skin lesions appear as flaccid thin walled fluid-filled bullae/vesicles
  • Lesions easily rupture leaving raw, denuded (stripped) erosions
  • Lesions are Nikolsky sign positive
  • Oral mucosal erosions (superficial blistering & erosions widespread within mouth, painful, slow to heal ulcers)
21
Q

What is the likely cause shown here ?

A

Pemphigus vulgaris

22
Q

What is the likely bullous disease shown ?

A

Pemphigus vulgaris

23
Q

What is the likely bullous disease shown ?

A

Pemphigus vulgaris

24
Q

How is pemphigus vulgaris diagnosed ?

A

Skin biopsy + DIF

25
What is the immunofluoresence appearance of pemphigus vulgaris ?
* Shows IgG on the surface of keratinocytes creating chiken-wire pattern (recall this is the green lines) * Acantholysis seen
26
What is the treatment of pemphigus vulgaris ?
* Local tx = TCS + Topical anaesthetics * Systemic tx = **Prednisolone** +/- any of the following for steroid sparing - azathioprine, dapsone, ciclosporin, plasmaphoresis
27
What is the prognosis of pemphigus vulgaris ?
Majority relapse. Mortality 10-20%
28
What is dermatitis herpetiformis ?
* It is an autoimmune blistering skin disorder * The name herpetiformis comes from the tendancy for blisters to arise in clusters
29
Who is most commonly affected by dermatitis herpetiformis (DH) ?
* People with **coeliacs disease** (\>90% of patients will have coeliacs) * Those with a FH of DH * Affects all ages but majority are young adults (15-40)
30
Describe the pathogenesis of DH
* Gluten triggers production of IgA antibodies & an autoimmune process that targets the skin & gut. * Regarding the skin the result is development of sub-epidermal blisters
31
Describe the distribution of DH
* Symmetrical distribution * Most commonly appears on the extensor aspect of the elbows & forearms, buttocks & scapulae, kness, face & scalp
32
What are the clinical features of DH ?
* Lesions often appear in groups/clusters * Characteristically small blisters on an erythematous urticarial base * Blisters are very itchy with rash usually preceeding blister formation * Blisters are often eroded & crusted due to scratching * Excoriations (lesions following trauma) * mucosal membrane lesions are rare
33
What is shown in this pic ?
DH
34
What is shown in this pic ?
DH
35
What is shown in this pic ?
DH
36
What is shown in this pic ?
DH
37
How is DH diagnosed ?
Skin biopsy + DIF
38
What additional investigations should be done in someone with DH ?
Investigations for diagnosing coeliacs: * 1st line = coeliacs serology IgA tTGA (IgA EMA) * 2nd line if serology pos = duodenal biopsy to confirm or exclude coeliacs
39
What is the immunofluoresence appearance of DH ?
Shows IgA deposition in a granular pattern in the upper dermis
40
What is the treatment of DH ?
**1st line = gluten-free diet + dapsone** if intolerant to daspone alternatives include tetracyclins, sulphapyridine or sulphamethocyoyradazine
41
What should you be vigalent for in someone with DH ?
NHL of the small bowel or anyother part of the body
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go over this
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go over this
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Go over the levels of blistering