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.