[Anti-p200 pemphigoid: a spectacular response to dapsone]

Area of Science:

• Dermatology
• Immunology
• Autoimmune diseases

Background:

• Subepidermal autoimmune bullous dermatoses (AIBD) are classified by clinical presentation and target antigen.
• A novel AIBD entity, anti-p200 pemphigoid, has been recently identified.

Observation:

• A patient presented with a severe, treatment-refractory bullous eruption.
• Standard bullous pemphigoid (BP) antibody testing was negative.
• Immunofluorescence showed IgG and C3 deposition at the dermal-epidermal junction, with IgG4 on the dermal side.
• Immunoblotting detected antibodies against a 200-kD epidermal antigen.

Findings:

• Diagnosis of anti-p200 pemphigoid was established despite atypical immunofluorescence and immunoblotting results.
• Anti-p200 pemphigoid autoantibodies target laminin gamma-1, an extracellular matrix protein crucial for dermal-epidermal adhesion.
• This condition is more prevalent in males, often presents in later life, and may involve mucous membranes and the head, with a higher incidence of scarring compared to BP.
• A significant association with psoriasis is noted in about one-third of cases.

Implications:

• Anti-p200 pemphigoid may be underdiagnosed, particularly in France.
• Consideration of anti-p200 pemphigoid is crucial for atypical bullous disease presentations.
• Immunoblotting for a 200-kD antigen confirms diagnosis.
• Dapsone demonstrates efficacy as a primary treatment modality.