This is the largest direct immunofluorescence (DIF) analysis of patients with histology-proven cutaneous leukocytoclastic vasculitis (LCV). To establish the correlation of deposition of immune complexes at the blood vessel walls with underlying causes and prognosis of LCV, we performed a retrospective study from January 2007 to December 2014. The patients are followed at the Department of Dermatology, Hospital Das Clínicas da Faculdade de Medicina da Universidade de São Paulo, a tertiary hospital at São Paulo, Brazil. We reviewed the data of 282 biopsy-proven LCV cases with DIF performed. For the statistical analysis, we included only patients with positive DIF exclusively in vessel walls (235/282 patients). We planned to find a correlation between the DIF profiles of LCV patients and the epidemiology data, underlying causes and prognosis. Ages ranged from five to 87 years old (yo), median age of 45 and 191/282 (67.73 %) were female individuals. DIF analysis showed positivity in 70.21 % of the samples, and C3 was the most frequent immunoreactant. Immunoglobulin A (IgA) deposition at the blood vessel wall was related to age and absence of autoimmune/inflammatory diseases. Immunoglobulin M (IgM) deposition at the blood vessel wall was related to females, autoimmune/inflammatory disorders, C3 and C4 consumption and antinuclear antibody and anti-SSA/anti-SSB positivity. Immunoglobulin G (IgG) deposition at the blood vessel wall was associated with age and positive ANCA; finally, C3 deposition at the blood vessel wall was associated with hematuria and renal involvement. Systemic involvement was present in 12.5 % cases of LCV patients. C3 deposits, the most frequent finding of this study, were related to renal involvement; IgA deposits to absence of autoimmune or inflammatory diseases; IgM deposition to the presence of autoimmune or inflammatory diseases and IgG deposits were associated with positive ANCA. DIF seems to be an important method to establish the prognosis and underlying etiology of LCV. Characterization of the immune complex at the blood vessel wall by DIF is relevant to determine underlying conditions related to LCV.

<b><i>Background:</i></b> Lichen planus (LP) can lead to severe scarring of the nail unit leading to anonychia. There are very few reports of squamous cell carcinoma (SCC) occurring in the lesions of ungual LP. <b><i>Objective:</i></b> The aim of this study was to revise the previously reported cases of SCC appearing in ungual LP and to present a new case. <b><i>Methods:</i></b> A PubMed search was performed with the terms “nail lichen planus” and “squamous cell carcinoma.” Reported cases as well as a new case were depicted in a table. <b><i>Results:</i></b> Only 2 indexed articles reporting 3 cases were found. All patients suffered of long-lasting scarring ungual LP. <b><i>Conclusions:</i></b> The occurrence of SCC in nail LP is rare. LP is not “premalignant” per se, but SCC might rarely arise in LP scars.

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