Pemphigus vulgaris

Pemphigus is characterized as a group of lethal blistering disorders defined by acantholysis (loss of keratinocyte to keratinocyte adhesion) that leads to the formation of intraepithelial blisters in mucous membranes and skin. The progress of acantholysis is induced by the attaching of circulating immunoglobulin G (IgG) autoantibodies to intercellular adhesion molecules. Patients with pemphigus develop mucosal erosions and/or flaccid bullae, abrasion, or furuncle on skin. The four main forms of the pemphigus group include pemphigus vulgaris, pemphigus foliaceus, immunoglobulin A (IgA) pemphigus, and paraneoplastic pemphigus. The other forms of pemphigus are determined by their clinical features, associated autoantigens, and laboratory results.

Panel Test:

● Immunogenetics:
  o HLA-A10, HLA-DR4/DQw3 (DRB1*0402), DR6/DQw1 (DQB1*0503).
● Immunopathology:
  o DIF on skin biopsies shows the deposition of IgG and C3 in the intercellular spaces of the epidermis, giving a chicken-wire appearance, in almost all cases.
  o IIF on monkey oesophagus gives a similar pattern in >90% of patients.
  o Diagnosis requires both DIF on a suitable biopsy and IIF on serum.
Comments: Low titres of serum antibodies giving a similar staining pattern have been reported in SLE, myasthenia gravis with thymoma, burns, and some cutaneous infections (leprosy).
● Autoantibodies:
  o anti Desmoglein-3 antibody (Dsg-3): Some patients also have antibodies to desmoglein-1 (Dsg-1).
Comment: A rare form of pemphigus, with a characteristic neutrophilic infiltrate, has been described in which the antibody is IgA and the autoantigens are desmocollin I and II, components of the desmosome. The DIF shows a chicken-wire staining pattern, located in the basal layers only with anti-IgA antiserum.