Leukocytoclastic vasculitis with and without IgA deposition is associated with renal damage: A case-control study

Leukocytoclastic vasculitis (LCV) is a small vessel vasculitis presenting with palpable purpura. Direct immunofluorescence (DIF) is routinely performed on skin biopsy to identify IgA deposition, which is thought to contribute to greater frequency of renal comorbidity associated with IgA vasculitis. Knowledge of characteristics between LCV with and without IgA deposition is limited. This study characterized presentations of LCV with and without IgA. Charts identified in the JHH pathologic database system with biopsy confirmed LCV between 2009-2018 were reviewed. Adult patients were stratified by presence of IgA by DIF on skin biopsy to compare demographics, comorbidities, clinical features, and hospitalization characteristics. Univariate analyses were performed using χ2 tests and t-tests in STATA. Of 162 biopsy confirmed LCV cases, DIF was performed on 118 (72.8%). IgA deposition in skin biopsy was present in 46 (39.0%) patients. Median age was 54 (IgA-) and 51 (IgA+). IgA- LCV was associated with elevated CRP (average IgA- 8.66 vs. IgA+ 3.41; p=0.015). Differences in comorbidities included pulmonary hypertension (IgA- 3.7%, IgA+ 14.0%; p=0.024), peripheral vascular disease (IgA- 22.6%, IgA+ 7.0%; p=0.025), and asthma (IgA- 14.1%, IgA+ 2.3%, p=0.035). No difference in renal involvement (hematuria, pyuria, or proteinuria) was observed (IgA- 60.7%, IgA+ 54.3%, p=0.545). There was no difference in prevalence of AKI or CKD at diagnosis (IgA- 28.4%, IgA+ 30.6%, p=0.810) or within 365 days (IgA- 31.5%, IgA+ 42.9%; p=0.230). Patients with LCV with and without IgA deposition are both at heightened risk of renal disease, suggesting all LCV cases should be followed for potential renal injury. Future studies should evaluate differences in pathogenesis and natural history and investigate the impact of DIF in the management of patients presenting with palpable purpura.