Distinct pattern of direct immunofluorescence in livedoid vasculopathy

There are discrepancies in findings on direct immunofluorescence (DIF) examinations for livedoid vasculopathy. We sought to assess the usefulness of DIF examinations as an adjunct to the diagnosis of livedoid vasculopathy. Clinical data and findings on DIF examinations were retrospectively collected from our immunofluorescence laboratory database on 27 patients with a histopathologic diagnosis of livedoid vasculopathy made between July 2002 and December 2008. The patterns of DIF were analyzed. Positive depositions of immunoreactants were found in 100%. A characteristic pattern of homogenous vascular deposition in both superficial and deep blood vessels was present in 96% (26/27) of specimens. The percentages of various immunoreactants were as follows: fibrinogen, 100%; complement component 3, 96%; immunoglobulin M (IgM), 85%; immunoglobulin A, 48%; and immunoglobulin G, 7%. Fibrinogen and IgM were the brightest deposits. The distinctive pattern of strong homogenous deposition of fibrinogen, complement component 3, and IgM in the superficial and deep plexuses was present in most cases of livedoid vasculopathy. This pattern provides a useful clue to its diagnosis.