A 59-year-old man having arteriosclerosis obliterans (ASO) was associated with the anti-i antibody (anti-i) of IgM class. His chief complaints were multiple painful ulcer formations on his both lower legs and he had been administered with mefenamic acid. Although laboratory tests revealed no findings suggestive of lymphoreticular malinancy nor infectious mononucleosis, elevated anti-EBV antibody titer (EB. VCA IgG 160×), positive direct Coombs' test and possible hemolytic anemia were recognized. So far, only several cases with anti-i have been reported in Japan, all of them having hematological disorders such as malignant lymphoma or Wiskott-Aldrich syndrome. In our case, the mechanism of the anti-i production might be attributable to increased i antigen due to ASO, immunological aberrations caused by mefenamic acid and polyclonal B cell activation due to EBV infection.
