[Anti-laminin 5 mucous membrane pemphigoid]

Area of Science:

• Dermatology
• Immunology
• Pathology

Background:

• Mucous membrane pemphigoid (MMP) is a chronic autoimmune blistering disease.
• It primarily affects mucosal surfaces, but cutaneous involvement can occur.

Observation:

• A 70-year-old patient presented with oral and skin erosions, particularly in perianal and inguinal regions.
• Histopathology revealed subepidermal blistering.
• Direct and indirect immunofluorescence showed IgG and C3 deposits at the dermal-epidermal junction and IgG autoantibodies targeting laminin 5 subunits.

Findings:

• Autoantibodies were identified against both processed and non-processed alpha3 and beta3 subunits of laminin 5.
• This confirmed the diagnosis of anti-laminin 5 mucous membrane pemphigoid.
• Immunoblot analysis using cultured human keratinocyte extracellular matrix was crucial for identifying the target antigen.

Implications:

• This case highlights the importance of immunofluorescence and immunoblotting in diagnosing rare autoimmune blistering diseases.
• Prompt diagnosis and combined therapy with dapsone and intravenous dexamethasone pulse therapy led to rapid clinical improvement.
• Understanding the specific autoantigen (laminin 5) aids in targeted treatment strategies for MMP.