AKT · Dermatology/Inflammatory & papulosquamouslow yield

Pemphigus vulgaris

Autoantibodies to desmoglein 3 — INTRA-epidermal acantholysis

Overview

An autoimmune INTRA-epidermal blistering disease: IgG autoantibodies against desmoglein-3 break the bonds between keratinocytes (acantholysis), so the split is high within the epidermis. The thin roof means blisters are FLACCID and rupture into painful EROSIONS, with a POSITIVE Nikolsky sign. Mucosal involvement is early and prominent, often the presenting feature.

Recognise

Flaccid, easily-ruptured blisters that quickly become painful erosions/crusts on the skin
Painful oral (mucosal) EROSIONS are often the first sign and may precede skin disease by months
Nikolsky POSITIVE (superficial intra-epidermal split — pressure shears the epidermis); typically middle-aged adults

Red flags

Widespread erosions → fluid/protein loss, sepsis (the main cause of death) — this is a serious, potentially life-threatening disease needing systemic immunosuppression

Differentials & how to tell them apart

Bullous pemphigoidelderly, TENSE blisters, Nikolsky NEGATIVE, mucosa usually spared, subepidermal split — pemphigus is flaccid, Nikolsky positive, mucosal, intra-epidermal

SJS/TENacute drug-induced, rapid sheet detachment, targetoid — not the chronic autoimmune course

Aphthous ulcers / oral lichen planusthe mucosal-only early phase can mimic these — biopsy persistent erosions

Paraneoplastic pemphigussevere mucositis + an underlying neoplasm (lymphoproliferative)

Clinical image

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Pemphigus vulgaris — clinical imagesDermNet

Investigations

Biopsy: histology (intra-epidermal split with acantholysis, "tombstone" basal layer) + DIRECT IMMUNOFLUORESCENCE showing intercellular IgG in a "chicken-wire/fishnet" pattern; anti-desmoglein-3 antibodies (ELISA, correlate with activity).

Management

Systemic corticosteroids (± rituximab) under specialist dermatology

1Confirm with biopsy + DIF (intercellular "chicken-wire" IgG). Treat with systemic corticosteroids, increasingly combined early with rituximab, under specialist care.Gate: Flaccid blisters/erosions + Nikolsky POSITIVE + prominent MUCOSAL disease = pemphigus vulgaris (intra-epidermal) — distinct from bullous pemphigoid (tense, Nikolsky negative, mucosa spared); pemphigus is the more dangerous and needs systemic immunosuppression, not just topical steroid
2Steroid-sparing agents (rituximab, azathioprine, mycophenolate); meticulous wound/mucosal care; monitor and treat infection (the leading cause of death).

Systemic corticosteroids (oral prednisolone) — mainstay to control the disease

Rituximab — first-line steroid-sparing agent for moderate-to-severe disease (increasingly early use)

Azathioprine / mycophenolate — other steroid-sparing immunosuppressants

Wound care + treat secondary infection — manage the erosions

Key points

Flaccid + Nikolsky positive + mouth-first = pemphigus (superficial split). It is more serious than pemphigoid — untreated it can be fatal from fluid loss and sepsis. Rituximab has transformed management.

Monitor & prognosis

Disease activity (anti-Dsg3), infection, immunosuppression effects.

Chronic and serious; much improved by systemic therapy (historically high mortality untreated).

Source: BAD Pemphigus vulgaris guideline; StatPearls