How is mixed cryoglobulinemic vasculitis diagnosed?
Detection of cryoglobulins in the right clinical setting is diagnostic. Given the fact that false-negative results are common due to sample mishandling, the absence of cryoglobulins does not exclude the diagnosis.
A high level of suspicion should be maintained if characteristic clinical and laboratory features are present. Elevated RF, low complement level, and the presence of a monoclonal gammopathy (especially when found together) may serve as a surrogate marker of cryoglobulinemia. Biopsy of affected tissue (typically skin) demonstrates leukocytoclastic vasculitis, and intravascular hyaline thrombi may also be seen. Immunofluorescence typically demonstrates Ig and C3 deposition. Biopsies of liver or bone marrow may demonstrate clonal expansions of B cells.
