The relationship between direct immunofluorescence findings and clinical and laboratory parameters in patients with cutaneous small vessel vasculitis

Objective: Cutaneous small-vessel vasculitis (CSVV) is a disease characterized histologically by leukocytoclastic vasculitis (LCV) and immune-complex deposition in small vessel walls. We aimed to evaluate the type of deposited immune complexes in patients with LCV and to determine the relationship between the immune-complex types and clinical and laboratory parameters. Materials and Methods: Patients who had been diagnosed as LCV histopathologically between 2000 and 2018 were retrospectively evaluated. Patients' medical records and pathology databases were reviewed to determine the demographic characteristics, clinical, laboratory, and histopathological findings. Direct immune fluorescence (DIF) findings to determine the immune-complex subtypes, including immunoglobulin A (IgA), immunoglobulin M (IgM), immunoglobulin G (IgG) or C3 deposition, were evaluated. Results: Sixty-eight patients were included in the study. A total of 36 (53%) patients had deposition in the perivascular or vessel walls, with at least one of IgA, IgM, IgG, or C3. IgA deposition was detected in 29 (42.6%) patients, IgM in 13 patients (19.1%), IgG in four patients (5.9%), and C3 in 31 patients (45.6%). Clinical features of the patients, including triggering factors, extracutaneous involvement, lesion localization, and skin findings, were compared with DIF findings. It was found no statistically significant difference between DIF-positive and DIF-negative groups (P > 0.05, for all). There was also no statistically significant difference in terms of laboratory findings between the groups (P > 0.05, for all). Conclusions: Our study showed that DIF findings did not play a role in determining the clinical findings, and they did not affect laboratory parameters in CSVV.