Blistering

Localised
Eczema	Pompholyx blisters on hands & feet, itching
Allergic Rxn	Include insect bites & topical applications
Psoriasis	Deep sterile non-itching blisters on soles & palms
Impetigo	Usually localised, Staph & Strep isolated
Herpes simplex	Itching lesions develop turbid blisters

Generalised
Eczema	Lichenification, crusting itching
Dermatitis herpetiformis	Itching, extensor surfaces, persisting, superficial blisters Coeliac disease. Linear deposits of IgA along basement membrane. Px - Dapsone, sulphapyridine, no gluten.
Chickenpox	Prodromal illness. Crops blisters, self limiting. May affect mucous membranes
Pityriasis lichenoides	Very to chickenpox but no infective agent. May last for months
Erythema multiforme	Deep blisters in target lesions. Mucous membranes. Drugs/bugs
Pemphigoid	Older patients. Trunk & flexures. Preceding erythema then deep tense blisters. Ab in dermo-epidermal junction. May cause scarring. Remits after months of PO steroids.
Pemphigus	Adults. Widespread superficial blisters. Mucous membrane erosions. Chronic. Nikolsky’s sign. High morbidity despite steroids & azathioprine.