A 38-year-old woman has had malaise and arthralgias for the past 14 months. On physical examination, she has scleral icterus and 1- to 3-cm areas of reddish-purple discoloration on her skin. Several of these areas show focal ulceration. Laboratory findings show total protein, 7.1 g/dL; albumin, 3.3 g/dL; AST, 127 U/L; ALT, 145 U/L; alkaline phosphatase, 80 U/L; total bilirubin, 4 mg/dL; and direct bilirubin, 3.1 mg/dL. Serologic test results are positive for anti-HCV and negative for anti-HBs and IgM anti-HAV. Urinalysis shows 4+ proteinuria and 1+ hematuria. CT scan of the abdomen shows a small amount of ascites, mild hepatomegaly, and no splenomegaly or lymphadenopathy. A biopsy specimen of an ulcerated skin lesion shows leukocytoclastic vasculitis involving the upper dermis. What is the most likely diagnosis?