Linear IgA Dermatosis

Linear IgA dermatosis (LAD) is a rare autoimmune bullous disorder characterized by linear deposits of IgA along the basement membrane zone. It commonly affects children between 6 months and 10 years of age, with a peak onset between 4-5 years.

Key Points:

• Most common autoimmune bullous disorder in children
• Also known as Chronic Bullous Disease of Childhood (CBDC)
• Usually idiopathic but can be drug-induced
• Self-limiting condition that typically resolves by puberty

Pathophysiology:

• Autoantibodies target multiple basement membrane zone antigens
• Primary antigen: LAD-1 (120-kDa fragment of BP180)
• Results in subepidermal blister formation
• Neutrophilic infiltrate in early lesions

Characteristic Presentation

• Vesicles and bullae on erythematous or normal-appearing skin
• "String of pearls" or "cluster of jewels" appearance
• Annular or polycyclic configuration
• Pruritic lesions

Distribution

• Perioral, periorbital regions
• Lower abdomen
• Perineal area
• Extensor surfaces of limbs

Mucosal Involvement

• Occurs in 60-70% of cases
• Oral mucosa most commonly affected
• Can involve conjunctiva, genitals
• May cause scarring if untreated

Diagnostic Criteria

• Clinical presentation
• Histopathology: Subepidermal blistering with neutrophilic infiltrate
• Direct immunofluorescence: Linear IgA deposits along basement membrane zone
• Indirect immunofluorescence: Circulating IgA autoantibodies (in 70% cases)

Differential Diagnosis

• Dermatitis herpetiformis
• Bullous impetigo
• Bullous pemphigoid
• IgA vasculitis (Henoch-Schönlein purpura)
• Epidermolysis bullosa

First-Line Treatment

• Dapsone (1-2 mg/kg/day)
• Monitor for hemolysis and methemoglobinemia
• G6PD screening before initiation

Alternative Treatments

• Sulfapyridine
• Systemic corticosteroids
• Colchicine
• Mycophenolate mofetil

Supportive Care

• Wound care for erosions
• Topical antibiotics if needed
• Pain management
• Nutritional support if oral involvement

Potential Complications

• Secondary bacterial infections
• Scarring (especially with mucosal involvement)
• Growth retardation (rare, in severe cases)
• Psychological impact

Monitoring

• Regular blood counts while on dapsone
• Assessment of disease activity
• Growth monitoring
• Quality of life evaluation