Dermatology, Venereology and Leprosy
Vesicobullous Disorders
Blistering diseases for MBBS and NEET-PG: pemphigus versus pemphigoid, Nikolsky sign, Tzanck test, immunofluorescence, dermatitis herpetiformis and treatment, mapped to NMC codes DR13.
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Vesicobullous Disorders
Blistering diseases for MBBS and NEET-PG: pemphigus versus pemphigoid, Nikolsky sign, Tzanck test, immunofluorescence, dermatitis herpetiformis and treatment, mapped to NMC codes DR13.
Vesicobullous disorders are the immunobullous diseases whose classification turns on blister depth. This chapter contrasts intraepidermal pemphigus with subepidermal pemphigoid, covers the Nikolsky and bulla-spread signs, the Tzanck test, immunofluorescence patterns, dermatitis herpetiformis, and the assessment and immunosuppressive treatment of blistering disease.
High-yield: Vesicobullous Disorders
- Vesicobullous disorders are blistering diseases, and the depth of the blister within the skin separates the main groups.
- Pemphigus vulgaris is an intraepidermal blistering disease caused by antibodies against desmoglein, which holds keratinocytes together.
- Pemphigus produces flaccid blisters that rupture easily to leave painful erosions, and oral involvement is often the first sign.
- The Nikolsky sign is positive in pemphigus: gentle lateral pressure on normal-looking skin shears off the epidermis.
- Bullous pemphigoid is a subepidermal disease of the elderly with tense blisters on an itchy urticarial base, and the Nikolsky sign is negative.
- Pemphigoid antibodies are directed against hemidesmosome proteins of the basement membrane zone.
- A Tzanck smear from a pemphigus blister shows rounded acantholytic cells that have lost their attachments.
- Direct immunofluorescence shows a net-like or fish-net intercellular pattern in pemphigus and a linear band along the basement membrane in pemphigoid.
- Dermatitis herpetiformis is an intensely itchy grouped vesicular eruption on the extensor surfaces, associated with coeliac disease and IgA deposits in the dermal papillae.
- The body surface area of blistering and denudation is estimated using the rule of nines to gauge severity and fluid needs.
- Extensive blistering carries risks of fluid and protein loss, secondary infection and sepsis, so care parallels that of a burn.
- Systemic corticosteroids are the mainstay for pemphigus and severe pemphigoid, often with steroid-sparing immunosuppressants.
- Dermatitis herpetiformis responds to dapsone and to a gluten-free diet.
- Pemphigus was historically fatal before corticosteroids, which underlines the importance of prompt immunosuppressive treatment.
Pemphigus versus pemphigoid
- **Blister level:** Pemphigus intraepidermal (flaccid); pemphigoid subepidermal (tense).
- **Nikolsky sign:** Positive in pemphigus; negative in pemphigoid.
- **Target:** Desmoglein in pemphigus; basement membrane hemidesmosomes in pemphigoid.
- **Immunofluorescence:** Fish-net intercellular in pemphigus; linear basement membrane band in pemphigoid.
NMC competencies in this chapter
- **DR13.1:** Aetiology, features and differentiation of vesicobullous disorders
- **DR13.2:** The Tzanck test, Nikolsky sign and bulla-spread sign
- **DR13.3:** Calculating the body surface area involved in vesicobullous disease
Frequently Asked Questions
What is the Nikolsky sign?
Gentle lateral pressure on apparently normal skin shears off the epidermis. It is positive in pemphigus and in toxic epidermal necrolysis, and negative in bullous pemphigoid.
How do pemphigus and pemphigoid differ?
Pemphigus is an intraepidermal disease with flaccid blisters, oral involvement and a positive Nikolsky sign, while pemphigoid is a subepidermal disease of the elderly with tense blisters and a negative Nikolsky sign.
What is dermatitis herpetiformis linked to?
It is associated with coeliac disease, shows IgA deposits in the dermal papillae, and responds to dapsone and a gluten-free diet.
How is the severity of blistering assessed?
The body surface area of blistering and denudation is estimated with the rule of nines, which guides fluid replacement and reflects the risk of infection, as in a burn.
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