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Dermatology week 2 > Bullous disease > Flashcards

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
Q

What is the immunofluoresence appearance of pemphigus vulgaris ?

A
  • Shows IgG on the surface of keratinocytes creating chiken-wire pattern (recall this is the green lines)
  • Acantholysis seen
26
Q

What is the treatment of pemphigus vulgaris ?

A
  • Local tx = TCS + Topical anaesthetics
  • Systemic tx = Prednisolone +/- any of the following for steroid sparing - azathioprine, dapsone, ciclosporin, plasmaphoresis
27
Q

What is the prognosis of pemphigus vulgaris ?

A

Majority relapse. Mortality 10-20%

28
Q

What is dermatitis herpetiformis ?

A
  • It is an autoimmune blistering skin disorder
  • The name herpetiformis comes from the tendancy for blisters to arise in clusters
29
Q

Who is most commonly affected by dermatitis herpetiformis (DH) ?

A
  • 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
Q

Describe the pathogenesis of DH

A
  • 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
Q

Describe the distribution of DH

A
  • Symmetrical distribution
  • Most commonly appears on the extensor aspect of the elbows & forearms, buttocks & scapulae, kness, face & scalp
32
Q

What are the clinical features of DH ?

A
  • 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
Q

What is shown in this pic ?

A

DH

34
Q

What is shown in this pic ?

A

DH

35
Q

What is shown in this pic ?

A

DH

36
Q

What is shown in this pic ?

A

DH

37
Q

How is DH diagnosed ?

A

Skin biopsy + DIF

38
Q

What additional investigations should be done in someone with DH ?

A

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
Q

What is the immunofluoresence appearance of DH ?

A

Shows IgA deposition in a granular pattern in the upper dermis

40
Q

What is the treatment of DH ?

A

1st line = gluten-free diet + dapsone

if intolerant to daspone alternatives include tetracyclins, sulphapyridine or sulphamethocyoyradazine

41
Q

What should you be vigalent for in someone with DH ?

A

NHL of the small bowel or anyother part of the body

42
Q

go over this

A
43
Q

go over this

A
44
Q

Go over the levels of blistering

A

Dermatology week 2 (22 decks)

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