IgA Pemphigus

  • Rare
  • Middle-aged or elderly
  • Rarely can be associated with IgA monoclonal gammopathy and IBD

Caused by tissue bound or circulating IgA type autoantibodies against desmosomal proteins (dsg1 / dsg3 in IEN type and Dsc1 in SCPD type) that bind target proteins → neutrophil infiltration and acantholysis

  • Vesiculopustular eruption coalescing into annular or circinate pattern with crusting
  • Hypopion may be seen
  • Trunk / proximal extremities > intertriginous
  • Mucosa, palms / soles usually spared
  • Possible complications: infections, malignancies
Variants:
  1. Subcorneal pustular dermatosis (SCPD) (identical to Sneddon-Wilkinson (SW) except for DIF being negative in SW
  2. Intraepidermal neutrophilic (IEN)

Similar approach to PnP: Lesional bx for H&E: Subcorneal neutrophilic pustules, no acantholysis Perilesional DIF: IgA intercellular, rarely IgG/C3 Other tests (as PV) to demonstrate antibodies, if IIF substrate is monkey esophagus

  • Dapsone → respond within 24-48hrs → taper to lower effective dose
  • Sulfapyridine/Sulfasalazine or acitretin 0.5-1mg/kg/day (if dapsone not tolerated)
  • Low to medium dose prednisone, photochemotherapy (Psoralen and ultraviolet A radiation, PUVA), narrowband ultraviolet B (NBUVB) with acitretin or colchicine
  • Mycophenolate mofetil
  • TNF inhibitors

  • Subcorneal pustular dermatosis
  • PF
  • Bullous impetigo
  • Dermatitis herpetiformis
  • Linear immunoglobulin A Bullous dermatosis
  • Pustular psoriasis