Blistering Skin Conditions

A differential-diagnosis approach to blistering skin lesions. See Bullous Pemphigoid and Dermatitis Herpetiformis for detail on the two most important chronic autoimmune causes.

Definitions

Fluid-filled skin lesions: vesicles are <5mm, bullae are >5mm. When blisters are de-roofed they form an erosion; the serous fluid that comes out forms a crust.

Acute blistering diseases may be generalised or localised, and due to infection or inflammation.

Acute generalised blistering diseases

• Atypical enterovirus infection — widespread vesicular eruption, clears in a few days.
• Chickenpox/varicella — scalp, face, mucosa, trunk.
• Eczema herpeticum — herpes simplex complicating atopic dermatitis.
• Discoid (nummular) eczema.
• Erythema multiforme — target lesions (see its own page).

• SJS/TEN — patients are very unwell, mucosal involvement, nearly always drug-induced, skin comes off in sheets (see Drug Reactions & SCARs).
• Drug hypersensitivity syndrome (DRESS) — morbilliform eruption which may blister, often with mucosal involvement and marked eosinophilia.
• Staphylococcal scalded skin syndrome — young children, unwell, red skin comes off in sheets.

Acute localised blistering conditions

• Dermatitis
• Bullous impetigo
• Chilblains — fingers and toes in winter, painful, purplish tender plaques
• Enteroviral vesicular stomatitis (hand, foot and mouth disease)
• Erysipelas
• Fixed drug eruption — recurring rash at the same site, occurring with an intermittently taken drug within 24 hours of rash onset, central blister
• Herpes simplex — umbilicated vesicles
• Herpes zoster
• Insect bites/stings
• Burns — friction, thermal, radiation, chemical

Chronic acquired blistering conditions

Many possible causes; usually requires biopsy to make the diagnosis.

• Bullous pemphigoid — cutaneous (not mucosal), elderly, eczematous or urticarial precursors (see its own page for full detail).

• Porphyria cutanea tarda — metabolic photosensitivity; skin fragility, bullae, and milia on the backs of the hands and face; middle-age onset.

• Other autoimmune blistering conditions to know alongside bullous pemphigoid: dermatitis herpetiformis (see its own page), pemphigus, pemphigoid gestationis, acquired epidermolysis bullosa, and linear IgA disease — all should be worked up (biopsy for histology and a fresh sample for direct immunofluorescence, which is time-sensitive — liaise with the lab/specialist on handling) and managed in conjunction with dermatology.