Abstract:

IgA vasculitis is a small vessel vasculitis subtype that typically presents with palpable purpura on the lower extremities. IgA vasculitis is important to differentiate from other subtypes due to an increased risk of systemic involvement. For this study, we aimed to investigate if any standard microscopy features can predict the presence of perivascular granular IgA deposits on direct immunofluorescence (DIF) microscopy. The study was approved by the Institutional Review Board. We performed a retrospective search of our electronic medical records for pathology reports from our internal and consultation practice (01/01/2010-10/05/2021) with a diagnosis of cutaneous vasculitis, leukocytoclastic vasculitis (LCV) or IgA vasculitis. Inclusion criteria included adult patients with research authorization, and a diagnosis of LCV with a DIF from the same region and period. A blinded dermatopathologist reviewed standard microscopy slides for pre-determined histopathological features. Fifty-six biopsies (42 patients) met inclusion criteria for IgA-, while 56 biopsies (48 patients) met inclusion criteria for IgA+. Eosinophil presence and mid and deep dermal inflammation were statistically more associated with IgA- (41/56 [73.2%] and 31/56 [55.4%] respectively) than IgA+ cases (28/56 [50.0%] and 14/56 [25.0%]; p=.049 and .006 respectively, Chi-squared test). Neutrophilic eccrine hidradenitis was observed more frequently in IgA- than in IgA+ cases [15/56 [26.8%] and 6/56 [10.7%], respectively, but did not achieve significance (p=.051). Other microscopic criteria recorded were not significantly different between the two groups (p>.05, Chi-squared and Fisher’s exact tests). In this retrospective study, we found that few histopathological features on standard microscopy tested could reliably predict for the presence of IgA perivascular deposition on DIF, emphasizing the importance of obtaining a skin biopsy for DIF in all patients with suspected cutaneous small vessel vasculitis.

Financial Disclosure:
No current or relevant financial relationships exist.

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Fangyi Xie, MB BChir