Cutaneous small-vessel vasculitis with predominant IgM or IgG immune deposits on direct immunofluorescence: What does it mean in clinical practice and how does it fit within the dermatologic addendum to the 2012 revised International Chapel Hill Consensus Conference Nomenclature of Vasculitides? A retrospective review of 14 patients at Mayo Clinic.

Cutaneous IgM/IgG immune complex vasculitis is a newly recognized provisional subtype of single-organ vasculitis that is clinically indistinguishable from IgA vasculitis. This retrospective case series evaluated the presence, clinicopathological characteristics and outcomes of patients with IgM and/or IgG dominance or codominance on direct immunofluorescence testing (2010-23). This review represents only the second study to date to characterize this population. Early analysis of 14 patients revealed that cutaneous IgM/IgG immune complex vasculitis was mainly skin limited, and treatment with topical and oral corticosteroids typically resulted in complete resolution without recurrence. Additionally, this study demonstrated that nearly two-thirds (64%) of patients with cutaneous small-vessel vasculitis with IgM and/or IgG dominance or codominance on direct immunofluorescence were ultimately found to have an underlying autoimmune connective tissue disease, cryoglobulinaemia, antineutrophil cytoplasmic antibody-associated vasculitis, infection or a drug-related cause. Therefore, it is imperative that clinicians perform a thorough investigation of this unique population to evaluate for potential underlying diseases and/or triggers.