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  • Intercellular immunoglobulin (Ig) A dermatosis (IAD) is a chronic vesicular and/or pustular autoimmune skin disease caused by IgA, not by IgG, antibodies.

  • Two major types: subcorneal pustular dermatosis (SPD)-type IAD and intraepidermal neutrophilic IgA dermatosis (IEN)-type IAD.

  • SPD-type IAD clinically shows superficial pustules on the intertriginous areas.

  • IEN-type IAD clinically shows atypical pustular skin lesions with a sunflower-like configuration.

  • Diagnosis is made by histopathology showing intraepidermal pustules, immunofluorescence detecting in vivo bound and/or circulating IgA antikeratinocyte cell-surface autoantibodies, and various biochemical and molecular biologic methods demonstrating reactivity with various autoantigens.

  • SPD-type IAD shows histopathologically subcorneal neutrophilic pustules.

  • IEN-type IAD shows histopathologically neutrophilic pustules in the middle epidermis.

  • Major autoantigens are desmogleins (Dsg) and desmocollins (Dsc), cadherin-type cell-to-cell adhesion molecules found in desmosomes.

  • Patients are treated mainly with dapsone and systemic corticosteroids; other treatment options include immunosuppressive agents, tetracycline, colchicine, plasmapheresis, retinoids, adalimumab, and psoralen and ultraviolet A.

This chapter discusses findings, pathogenesis, diagnosis, and treatments for intercellular immunoglobulin (Ig) A dermatosis (also called IgA pemphigus): Other synonyms are intraepidermal neutrophilic IgA dermatosis, intercellular IgA vesiculopustular dermatosis and IgA pemphigus foliaceus.

In addition to clinical and histopathologic assessments, detection of autoantibodies to the skin by immunofluorescence is still a hallmark for the diagnoses of various autoimmune bullous diseases (AIBDs), which are organ-specific autoimmune diseases of the skin and mucous membranes.1-4 In addition, according to the progress in recent biochemical and molecular biologic techniques, various methods detecting autoantigen, including immunoblotting and enzyme-linked immunosorbent assays (ELISAs), are performed to make precise diagnoses of various AIBDs.1-8 Based on the results of these antigen detection analyses, AIBDs are currently classified into a large number of different diseases with distinct autoantibodies and autoantigens.1,2

The term intercellular IgA dermatosis (IAD) (also frequently called IgA pemphigus) refers to a group of AIBDs of skin and mucous membranes. IAD is characterized clinically by pustular skin lesions, histopathologically by intraepidermal neutrophilic pustules, and immunopathologically by in vivo bound and circulating IgA antibodies directed against the keratinocytes cell surfaces.9-14

This disease entity was first reported by Daniel Wallach.15 IAD/IgA pemphigus shows variable clinical, histopathologic, and immunologic features. As a result, this condition has been reported under a variety of names, including IAD,14 intraepidermal neutrophilic IgA dermatosis (IEN),16 intercellular IgA vesiculopustular dermatosis,17 and IgA pemphigus foliaceus.18

However, clinical, histopathologic, and immunologic features of this disease are considerably different from those in classical IgG types of pemphigus. Therefore, the term IAD was proposed as the name most suitable for this disorder.9-11,14

In the current classification of IAD,9-13 2 major subtypes of IAD are subcorneal pustular dermatosis (SPD)-type IAD and IEN-type IAD. There also are minor subtypes, including IgA pemphigus vegetans (PVeg), IgA pemphigus foliaceus (PF), IgA pemphigus vulgaris (PV), and undetermined-type IAD. Table 57-1 outlines the classification of the ...

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