Pemphigus Vulgaris

Pemphigus vulgaris is a rare chronic blistering skin disease and the most common form of pemphigus. Derived from the Greek word pemphix, meaning blister, it is classified as a type II hypersensitivity reaction where antibodies form against desmosomes.

Desmosomes function to bind certain layers of the skin together. When attacked, the skin layers separate, creating blisters due to acantholysis, or the breaking apart of intercellular connections.

The condition behaves similarly to a severe burn and progresses without treatment.

Signs and Symptoms

Pemphigus vulgaris typically presents with oral blisters on the buccal and palatine mucosa, but it can also involve cutaneous blisters and affect other mucosal surfaces such as the conjunctiva, nose, oesophagus, genitals, and anus. Blisters often erode, leaving ulcerated lesions.

A positive Nikolsky sign (skin blistering upon slight rubbing) is indicative of the disease. Severe pain while chewing can lead to weight loss and malnutrition.

Pathophysiology

Pemphigus vulgaris is an autoimmune disease caused by antibodies against desmoglein 1 and 3 in desmosomes. This results in the loss of cohesion between keratinocytes in the epidermis, disrupting the skin's barrier function.

Histologically, the basal keratinocytes remain attached to the basement membrane, creating a characteristic "tombstoning" appearance. The disease is characterised by extensive flaccid blisters and mucocutaneous erosions, with severity directly proportional to desmoglein 3 levels.

Diagnosis

Diagnosing pemphigus vulgaris can be complex due to its rarity. Early symptoms include oral erosions or skin blisters, which can be itchy or painful.

A punch biopsy examined by direct immunofluorescent staining is the gold standard for diagnosis, revealing acantholytic cells. These findings can also be seen on a Tzanck smear.

The disease is easily confused with impetigo and candidiasis but can be differentiated by the lack of response to antibiotics and specific immunological tests.

Treatment

Historically, corticosteroids and immunosuppressive medications have been used to manage pemphigus vulgaris. However, steroids have significant side effects, so their use is minimised.

Monoclonal antibodies like rituximab have become the preferred treatment, showing success in inducing remission, especially when initiated early. Rituximab combined with intravenous immunoglobulin has led to long-term remission in some cases.

Other potential treatments being looked at include anti-CD20 drugs like ocrelizumab, veltuzumab, and ofatumumab.

Epidemiology

Pemphigus vulgaris is a rare disease, affecting 1 to 5 people per million in the UK, with similar incidence rates worldwide. It typically appears after the age of 50 and is not contagious.

Some populations, such as Ashkenazi Jews and individuals of Mediterranean, North Indian, and Persian descent, have a higher prevalence. Historically, untreated pemphigus vulgaris had a high mortality rate, but modern treatments have significantly improved outcomes.

Research

Recent research has focused on genetically modified T-cells to target and eliminate autoreactive B cells specific to desmoglein. These treatments aim to provide a more targeted approach than current therapies like rituximab, which indiscriminately attacks all B cells, compromising the body's ability to control infections.

Early studies in mice have shown promising results.

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Self-assessment MCQs (single best answer)

What is the primary mechanism behind the formation of blisters in pemphigus vulgaris?

Which age group is most commonly affected by pemphigus vulgaris?

What is a positive Nikolsky sign indicative of?

What histological feature is characteristic of pemphigus vulgaris?

Which antibody is considered pathogenic in pemphigus vulgaris?

What is the gold standard for diagnosing pemphigus vulgaris?

Which treatment has shown to be increasingly effective as first-line therapy for pemphigus vulgaris?

Which population has a higher prevalence of pemphigus vulgaris?

Which part of the body is most commonly affected by initial blisters in pemphigus vulgaris?

What significant side effect is associated with the use of corticosteroids in the treatment of pemphigus vulgaris?