Immunobullous diseases Flashcards

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1
Q

List 3 immunobullous diseases

A

Bullous pemphigoid
Pemphigus vulgaris
Dermatitis Herpetiformis

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2
Q

What are the 2 types of blisters?

A

sub-epidermal
intra-epidermal

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3
Q

Describe sup-epidermal blisters

A

thick-walled
tense
hemidesmosomes (attach basal keratinocytes to basal membrane zone, BMZ - interface between dermis and epidermis)
Pemphigoid

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4
Q

Describe intra-epidermal blisters

A

thin-walled
flaccid
desmosomes (keratinocyte adhesion junctions)
keratin cytoskeleton
Pemphigus

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5
Q

Describe bullous pemphigoid

A

acquired autoimmune sub-epidermal blistering disease
itchy rash - eczematous or urticated
blisters - tense (vesicles and bullae)
localised or widespread
more likely to affect limbs than pemphigus vulgaris

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6
Q

Bullous pemphigoid investigations

A

biopsy:
- histology - sub-epidermal split
- direct immunofluorescence (band of IgG +/- C3)
Indirect immunofluorescence (circulating bullous pemphigoid antibodies)

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7
Q

Bullous pemphigoid treatment

A

oral steroids
doxycycline
nicotinamide
+/- azathioprine

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8
Q

Describe pemphigus vulgaris

A

acquired autoimmune disease
mucocutaneous blisters
IgG to desmosomal antigens
40-60 years old
oral ulcers precede rash
sore rash rather than itchy

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9
Q

Pemphigus vulgaris examination findings

A

mouth ulcers
erosions of skin
fragile/flaccid blisters
Nikolsky sign on scalp, face, chest, axillae, groin, umbilicus, back

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10
Q

What is Nikolsky sign?

A

dislodging of epidermis by lateral finger pressure leads to an erosion or extension of a blister

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11
Q

Pemphigus vulgaris investigations

A

biopsy
- histology - intra-epidermal split
- direct immunofluorescence (band of IgG +/- C3 around epidermal cells, ‘chickenwire’ pattern)
Indirect immunofluorescence (circulating pemphigus vulgaris antibodies)
titre proportional to activity

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12
Q

Pemphigus vulgaris treatment

A

high dose oral steroids
azathioprine
plasmapheresis
IV Ig

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13
Q

Prognosis of pemphigus vulgaris

A

infection
fluid and electrolyte imbalance
mortality 5-15%

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14
Q

Describe dermatitis herpetiformis

A

autoimmune blistering disease
all have gluten-sensitive enteropathy (coeliac disease)
associated with other autoimmune conditions (DM, thyroid, pernicious anaemia, SLE)

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15
Q

Presentation of dermatitis herpetiformis

A

age onset 20-60
very itchy rash
blisters (herpetiform)

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16
Q

What does dermatitis herpetiformis look like?

A

erythematous papules + blisters
lots of excoriations
extensor aspects (elbows, knees and buttocks)
may be more widespread
mucous membrane not involved

17
Q

Dermatitis herpetiformis investigations

A

biopsy
- histology - sub-epidermal blister
- direct immunofluorescence (uninvolved skin), granular deposits IgA in dermal papillae
distal duodenal biopsy (to diagnose coeliac)
antiendomysial and tissue transglutaminase antibodies

18
Q

Dermatitis herpetiformis treatment

A

gluten free diet (rash resolves 2-3 years on diet)
dapsone
sulphonamides:
- sulphoamethoxypyridazine
- sulphapyridine

19
Q

Dapsone side effects

A

headaches
depression
lethargy
methaemoglobinaemia
haemolytic anaemia (severe in G6PD deficiency)
neuropathy

20
Q

Side effects of sulphonamides

A

bone marrow suppression (especially neutrophils)
nausea
depression
rashes
hepatitis
interstitial pneumonitis

21
Q

Oral steroids side effects

A

hypertension
diabetes
peptic ulceration
cataracts
skin thinning
osteopenia/osteoporosis
mental disturbances
weight gain
adrenal suppression
muscle wasting (proximal myopathy)
increased susceptibility to infection

22
Q

Azathioprine side effects

A

GI disturbance (nausea, vomiting, diarrhoea)
bone marrow suppression
liver damage

23
Q

What type of bullae form in pemphigus vulgaris?

A

intraepidermal bullae

24
Q

What type of bullae form in bullous pemphigoid?

A

subepidermal bullae

25
Q

What skin lesion forms in dermatitis herpetiformis?

A

vesicles