Immunobullous diseases

Question 1

List 3 immunobullous diseases

Answer 1

Bullous pemphigoid
Pemphigus vulgaris
Dermatitis Herpetiformis

Question 2

What are the 2 types of blisters?

Answer 2

sub-epidermal
intra-epidermal

Question 3

Describe sup-epidermal blisters

Answer 3

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

Question 4

Describe intra-epidermal blisters

Answer 4

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

Question 5

Describe bullous pemphigoid

Answer 5

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

Question 6

Bullous pemphigoid investigations

Answer 6

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

Question 7

Bullous pemphigoid treatment

Answer 7

oral steroids
doxycycline
nicotinamide
+/- azathioprine

Question 8

Describe pemphigus vulgaris

Answer 8

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

Question 9

Pemphigus vulgaris examination findings

Answer 9

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

Question 10

What is Nikolsky sign?

Answer 10

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

Question 11

Pemphigus vulgaris investigations

Answer 11

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

Question 12

Pemphigus vulgaris treatment

Answer 12

high dose oral steroids
azathioprine
plasmapheresis
IV Ig

Question 13

Prognosis of pemphigus vulgaris

Answer 13

infection
fluid and electrolyte imbalance
mortality 5-15%

Question 14

Describe dermatitis herpetiformis

Answer 14

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

Question 15

Presentation of dermatitis herpetiformis

Answer 15

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

Question 16

What does dermatitis herpetiformis look like?

Answer 16

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

Question 17

Dermatitis herpetiformis investigations

Answer 17

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

Question 18

Dermatitis herpetiformis treatment

Answer 18

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

Question 19

Dapsone side effects

Answer 19

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

Question 20

Side effects of sulphonamides

Answer 20

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

Question 21

Oral steroids side effects

Answer 21

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

Question 22

Azathioprine side effects

Answer 22

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

Question 23

What type of bullae form in pemphigus vulgaris?

Answer 23

intraepidermal bullae

Question 24

What type of bullae form in bullous pemphigoid?

Answer 24

subepidermal bullae

Question 25

What skin lesion forms in dermatitis herpetiformis?

Answer 25

vesicles