Clinicopathologic features of IgG/IgA pemphigus in comparison with classic (IgG) and IgA pemphigus.

BACKGROUND: The pemphigus group is characterized by the presence of circulating immunoglobulins against desmosomes. IgG/IgA pemphigus is defined by the presence of IgG and IgA cell surface deposits upon direct immunofluorescence (DIF) and/or circulating IgG and IgA autoantibodies upon indirect immunofluorescence. Previous reports of patients with IgG/IgA pemphigus are sparse. Whether IgG/IgA pemphigus is best classified as a subtype of IgG (classic) pemphigus or IgA pemphigus, or as a distinct entity, has yet to be determined.

OBJECTIVES: We compared the features of patients with IgG/IgA pemphigus to those of IgG pemphigus and IgA pemphigus.

METHODS: Retrospective clinicopathologic study of patients with IgG, IgG/IgA, and IgA pemphigus evaluated at our clinic (1993-2013).

RESULTS: We included 26, 13, and seven patients with IgG, IgG/IgA, and IgA pemphigus, respectively. Patients with IgG/IgA pemphigus did not differ significantly from patients with IgG pemphigus in terms of clinical and microscopic features, DIF findings, anti-desmoglein antibody values, and treatments required. However, patients with IgG/IgA pemphigus were significantly different from patients with IgA pemphigus regarding intertriginous distribution (P = 0.038) and pustular lesions (P < 0.001), acantholysis (P = 0.043), and presence of intercellular C3 deposits on DIF (P < 0.001).

CONCLUSION: Comparative clinicopathologic data imply that IgG/IgA pemphigus may best be regarded as a variant of IgG pemphigus and distinct from IgA pemphigus.