Pemphigus vulgaris and bullous pemphigoid - the acute presentation

pemphigus · pemphigus vulgaris · bullous pemphigoid · autoimmune blistering disease · immunobullous disease

Two autoimmune blistering diseases that differ in depth, and that difference decides how sick the patient is.

URGENT DERMBand A

Red flags

Extensive erosions with fluid loss, pain or secondary infection - barrier failure needs admission
Inability to eat or drink because of mouth erosions
Any suggestion this is instead an acute drug reaction - a rapid onset with fever and a new drug points to epidermal necrolysis, which goes to a burns centre
Sepsis through eroded skin
Ocular or laryngeal mucosal involvement - suggests mucous membrane pemphigoid and needs urgent specialist assessment

Recognise

On light skin

Pemphigus vulgaris: flaccid, fragile blisters that rupture almost immediately, leaving painful raw erosions, with a positive Nikolsky sign. Bullous pemphigoid: tense, dome-shaped blisters on red or urticarial plaques that remain intact for days, intensely itchy, with a negative Nikolsky sign.

On brown and black skin

The blisters and erosions are tone-independent, but the inflammatory background of bullous pemphigoid is not - the urticarial plaques on which the blisters sit may be violaceous, hyperpigmented or barely visible rather than red, so an early pre-bullous pemphigoid presenting as itch alone is easily dismissed. In pemphigus, mucosal erosions are the presenting feature in most patients and the mouth is unaffected by skin pigment, so examine it. Healing in both leaves conspicuous and long-lasting post-inflammatory hyperpigmentation, which patients may find as troubling as the blisters and which should not be read as active disease.

In any skin tone

Flaccid and fragile, breaking early, mouth involved, Nikolsky positive - pemphigus vulgaris, a more unwell patient with a deeper split
Tense and intact, very itchy, mouth spared, Nikolsky negative - bullous pemphigoid, usually elderly
Painful mouth erosions preventing eating and drinking are the commonest first presentation of pemphigus vulgaris
Bullous pemphigoid may present with weeks of intense itch and urticarial plaques before any blister appears
Course over weeks, without the acute drug prodrome of epidermal necrolysis

Distribution

Pemphigus vulgaris begins in the mouth in most cases, then the scalp, face and trunk. Bullous pemphigoid favours the flexures, trunk and limbs, and usually spares the mouth.

Photographs

Pemphigus vulgaris. What you see are erosions and crusts, not blisters - the split is high in the epidermis, so the blister roof is too thin — Pemphigus vulgaris. **What you see are erosions and crusts, not blisters** - the split is high in the epidermis, so the blister roof is too thin to survive and has already gone by the time the patient arrives. Pemphigus begins in the mouth in most cases and the skin follows; a patient with painful oral erosions and scattered facial crusts has this until proven otherwise. Nikolsky's sign is positive.
Fitzpatrick IV-VI (Fitzpatrick type estimated from the photograph, not stated by the source) · Sajid Sharif · Wikimedia Commons - pemphigus vulgaris of the face · CC0 1.0

Bullous pemphigoid after the blisters have burst: broad denuded areas with a collarette of blister roof still attached at the edge, alongsid — Bullous pemphigoid after the blisters have burst: **broad denuded areas with a collarette of blister roof still attached at the edge**, alongside older healing patches. The split here is deeper, below the epidermis, so the blisters are tense and survive long enough to be seen - but by the time of presentation many have ruptured. Pemphigoid is a disease of older people, usually spares the mouth, and often itches for weeks before any blister appears.
Fitzpatrick I-III (Fitzpatrick type estimated from the photograph, not stated by the source) · Ibrahim Husain Meraj · Wikimedia Commons - bullous pemphigoid of the back · CC BY-SA 4.0

Provenance for every photograph in this library: image licences. How much of the corpus still has no darker-skin photograph: skin tone coverage.

Mimics

Stevens-Johnson syndrome / toxic epidermal necrolysis — Both blister with mucosal erosions and a positive Nikolsky in pemphigus; necrolysis is drug-triggered and evolves over days, immunobullous disease over weeks
Staphylococcal scalded skin syndrome — Both shear superficially with a positive Nikolsky; SSSS is a febrile illness of young children and spares mucosa
Eczema herpeticum — Both give crusted erosions; herpeticum's erosions are monomorphic, punched-out and on eczematous skin
Erythema multiforme major — Both give mucosal erosions with blistering; EM major has target lesions and is usually herpes-driven

What to do in the ED

Establish the pattern before treating: is the blister flaccid or tense, is the mouth involved, is Nikolsky positive - and document it, because the answer determines urgency
Do not start systemic corticosteroid in the ED without dermatology discussion; treatment is guided by diagnosis, and a skin biopsy with immunofluorescence is needed to confirm it
Refer to dermatology. Pemphigus vulgaris needs urgent specialist assessment; bullous pemphigoid needs prompt assessment but is less often an emergency
Dress eroded skin with non-adherent dressings, provide adequate analgesia, and swab if there is any sign of secondary infection
Mouth care and dietetic input where oral erosions are limiting intake; assess hydration
Admit for extensive disease, barrier failure, inability to maintain oral intake, or secondary infection
Take a careful drug history anyway - both conditions have recognised drug-induced forms

Disposition

URGENT DERM

Urgent dermatology for diagnosis by biopsy and immunofluorescence. Admit for extensive erosion, uncontrolled pain, inability to eat or drink, or secondary infection - pemphigus vulgaris substantially more often than bullous pemphigoid.

Safety-netting

While you are waiting for the dermatology appointment: return if the blisters spread quickly, if the skin becomes hot, increasingly painful or smells offensive, if you develop a fever, or if soreness in the mouth stops you eating or drinking. Broken skin is an open wound - it can become infected and it loses fluid, so do not wait for the appointment if any of that happens.

Sources

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