A case of duodenal diverticulitis in a patient receiving tocilizumab for rheumatoid arthritis

　A Japanese woman was diagnosed with rheumatoid arthritis at the age of 41. At the age of 56, her rheumatoid arthritis worsened and a subcutaneous injection of tocilizumab and oral prednisolone was administered, which led to an improvement of arthritis. At the age of 57, right lower abdominal pain and vomiting suddenly appeared. Abdominal computed tomography showed a parapapillary diverticulum in the descending duodenum. The diverticulum was filled with residue, and an inflammation of the surrounding adipose tissue was observed; no free air was found. The patient was diagnosed with duodenal diverticulitis and treated with antibiotics, which resulted in an uneventful recovery. The maximum value of CRP was 1.88㎎/dL on the third day of hospitalization. Esophagogastroduodenoscopy performed on the 8th day of hospitalization revealed a parapapillary diverticulum with adhesion of pus and redness of the mucosa at the opening of the diverticulum, consistent with diverticulitis. This case highlights that diverticulitis in infrequent areas such as the duodenum may occur in patients who are treated with tocilizumab. In addition, inflammation of diverticulitis may be underestimated because abnormal laboratory values such as those induced by inflammatory reactions are less likely to occur during tocilizumab treatment.

症例報告(Case Reports)