Atypical presentation and prolongation of retroperitoneal abscess after emergency surgery for perforated ascending colon cancer in a patient receiving anti-interleukin-6 receptor monoclonal antibody therapy

Tocilizumab is an anti-interleukin-6 receptor monoclonal antibody which was recently approved for the treatment of inflammatory arthritis and Castleman disease. Because tocilizumab suppresses immunological reactions, the more frequent occurrence of infections with atypical presentations is a conceivable complication after abdominal surgery. Herein, we would like to describe a case of a prolonged abdominal abscess with subtle abdominal pain after surgery for perforated ascending colon cancer in a patient with Castleman disease treated by tocilizumab.