110 LETTER If confirmed in a larger series of patients with MC, these findings could definitively clarify the pathogenetic role of HCY in cryoglobulinemic vasculitis. Luca La Civita, M.D. Anna Linda Zignego, M.D. Elisabetta Bemacchi, M.D. Monica Monti, B.S. Paolo Fabbri, M.D. Clodoveo Ferri, M.D. University of Pisa Pisa, Italy, and University of Florence Florence, Italy REFERENCES I. Ferri C, La Civita L, Longombardo G, Greco F, Bombardieri S. Hepatitis C virus and mixed cryoglobulinaemia, Eur J Clin Invest 1993; 23:399-405 2. Cohen SJ, Pittelkow MR, Su WPD. Cutaneous manifestations of cryoglobulinemia: clinical and histopathologic study of seventy-two patients. JAm Acad Dermatol 1991; 25:21-27 3. Ferri C, Monti M, La Civita L, Longombardo G, Greco F, Pasero G, et a1. Infection of peripheral blood mononuclear cells by hepatitis C virus in mixed cryoglobulinemia. Blood 1993; 82:3701-3704 4. Ferri C, Marzo E, Longombardo G, Lombardini F, La Civita L, Vanacore R, et al. Interferon-alpha in mixed cryoglobulinemia patients: a randomized, crossover-controlled trial. Blood 1993; 81:1132-1136 In response: Dr. La Civita and colleagues aptly point out the association between chronic hepatitis C virus (HCY) infec- tion, mixed cryoglobulinemia, and leukocytoclastic vasculitis. This letter can be added to a burgeoning amount of evidence that implicates HCY infection as a causative factor for cutaneous vasculitis. 1,2 Mayo Clin Proc, January 1996, Vol 71 All these case reports have common themes. The onset of cutaneous vasculitis seems to occur several years after the patient's initial exposure to or infection with HCY. Al- though many of the patients have risk factors for HCY infection, the cause of infection is unapparent in many cases. Liver function test results are usually increased at the time of diagnosis of leukocytoclastic vasculitis and HCY infection; however, in some cases, the test results are normal, Thus, all patients with leukocytoclastic vasculitis of unknown cause should be assessed for HCY infection. Other common labo- ratory abnormalities in addition to mixed cryoglobulinemia include an increased rheumatoid factor and decreased complement studies, especially C4. Treatment of the HCY infection seems to diminish cutaneous vasculitis, inasmuch as many of these patients have responded favorably to inter- feron therapy. Additional clinical and therapeutic manifesta- tions of this disease continue to unravel at a rapid pace. Lawrence E. Gibson, M.D. Mazen S. Daoud, M.D. Mayo Clinic Rochester Rochester, Minnesota Rokea A. el-Azhary, M.D. Mayo Clinic Jacksonville Jacksonville, Florida REFERENCES 1. Daoud MS, el-Azhary RA, Gibson LE. Chronic hepatitis C, cryoglobulinemia and cutaneous leukocytoclastic vasculitis: clinical, pathological, and immunopathological study of 10 patients. JAm Acad Dermatol [in press] 2. Karlsberg PL, Lee WM, Casey DL, Cockerell CJ, Cruz PO Jr. Cutaneous vasculitis and rheumatoid factor positivity as pre- senting signs of hepatitis C virus-induced mixed cryoglobulinemia. Arch Dermatol 1995; 131:1119-1123 The Editor welcomes letters and comments, particularly pertaining to recently published articles in the Mayo Clinic Proceedings. A letter should be no longer than 500 words, contain no more than 5 references, and be in a double-spaced, typewritten format. The letter should be signed. It is assumed that appropriate letters may be published, at the discretion of the Editor, unless the writer indicates otherwise. The Editor reserves the right to edit letters in accordance with the Mayo Clinic Proceedings style and to abridge them if necessary. For personal use. Mass reproduce only with permission from Mayo Clinic Proceedings.