RESUMO
BACKGROUND: Direct immunofluorescence (DIF) findings in patients with livedoid vasculopathy (LV) may have benefits for disease differentiation when clinical presentations and/or histopathological findings are inconclusive. AIM: To investigate DIF findings in patients with a clinical and histopathological diagnosis of LV. METHODS: DIF findings of 62 patients with LV were analysed, and the published literature in the PubMed database was also reviewed and summarized. RESULTS: This study demonstrated deposition of immunoreactants in blood vessels (BVs) in 59 of the 62 patients (95.2%), and almost all cases were positive for a combination of multiple immunoreactants. Complement C3 and IgM formed the most common combination. The most common pattern was deposition in BVs and at the dermoepidermal junction (DEJ) (59.3%), followed by deposition in BVs alone (40.7%). Immunoreactant deposition in BVs involved superficial BVs with or without deep BVs. The median age of patients with positive DIF findings was significantly higher than that of patients with negative DIF findings for LV (P < 0.03). More recent lesions (present for < 6 months) had a significantly higher percentage of positive results than older lesions (present for ≥ 6 months) (85.2% vs. 14.8%, respectively; P < 0.001). CONCLUSION: In both the present study and in the published literature, DIF study in patients with LV showed positive immunoreactants ranging from 42.9% to 100%. C3 and IgM were the most common immunoreactants deposited in BVs, while the most common pattern was immunoreactant deposition in BVs and at the DEJ. Older patients and those with more recent lesions (< 6 months) had a significantly higher percentage of positive DIF results for LV than did younger patients and those with older lesions (≥ 6 months).