Blistering rashes

Question 1

TERMINOLOGY
i) what is a vesicle?
ii) what is a bulla?
iii) what is crust

Answer 1

i) vesicle - small blister <5mm
ii) bulla - large blister larger than 1cm
iii) exudation of serous fluid forms a crust

Question 2

PEMPHIGUS VULGARIS
i) what is it caused by?
ii) how is it characterised? (2) where are lesions most commonly found?
iii) name three things it may be triggered by
iv) how do patients usually first present?
v) what is the characteristic of blisters seen

Answer 2

i) autoimmune cause
ii) charac by painful blusters and erosions on skin and mucus membranes - most commonly inside the mouth
iii) triggered by drugs eg ACEi, ARBs, penicillins or cancer or infection or trauma
iv) most patients present with lesions on mucus membranes such as mouth and genitals > blister a few weeks/months
v) thin walled blisters that rupture easily > itchy and painful erosions

Question 3

PEMPHIGUS VULGARIS DX AND TX
i) what must be done for diagnosis? (2) what is seen on histologu?
ii) what is the primary aim of treatment? (3)
iii) what drug is given for mainstay of tx?
iv) what topical tx can be given

Answer 3

i) biopsy the blister and adjacent skin to a lesion
- see rounded seperated kerattinocytes
ii) decrease blister formation, prevent infections and promote healing of blisters and erosions
iii) give corticosteroids systemtically - oral prednisolone or IV methylprednisolone
iv) topical steroid or emollients

Question 4

BULLOUS PEMPHIGOID
i) what is it? what age does it most commonly present in?
ii) name three things it may be associated with? which drug class are most commonly associated with it (2)
iii) what causes it?
iv) what is the main feature? name three others? how does it differ from pemphigus?

Answer 4

i) autoimmune subepidermal blistering disease
* most common presents in people >80yrs
ii) assic with HLA (genetic predis), neuro disease, psoriasis (PDT), malignancy
* common assoc with PD1 inhibitors and DPP4 inhibitors
iii) attack on basement membrane of epidermis by IgG and IgE and activated T cells
iv) severe itch and large tense fluid filled blisters (bullae) which rupture > crusted erosions
* non specific rash seen before blisters appear
* ezcema areas
* annular (ring shaped) lesions
* clear or cloudy blister fluid
* affect flexor aspect of the lumbs
* differs from pemphigus as blisters are tense in pemphigus they are thin walled and rupture easily

Question 5

DX AND TX OF BULLOUS PEMPHIGOID
i) which two things are involved in dx?
ii) what is given to treated limited disease (<10% body surface)? what is given to relieve itch and dryness? what abx can be given?
iii) which drug tx are most patients given?
iv) which score is used to look for skin and mucus membrane activity?

Answer 5

i) typical bullae > clinical dx
biopsy of early blister and non blistered inflammed skin
direct immunofluorescence of adjacent blister skin looks for antibodies along the BM
ii) limited disease - topical steroids eg clobetasol
itch and dryness - topical steroids and emollients
also give abx (tetracycline eg doxy) doxy can be effective on its own for mild disease (without steroids as it has less side effects)
iii) most patients given steroid tablets eg prednisolone - takes a few weeks for blisters to stop appearing
iv) bullous pemphigoid disease area index (BPDAI)