Blistering = Please note the three "D"s - Development, Duration, Distribution (± itch)

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 Similar 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.
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