Two Cases of Acute Diverticulitis Following Ocrelizumab Infusion in Patients With Multiple Sclerosis.

Ocrelizumab is an anti-CD20 monoclonal antibody used to treat primary progressive and relapsing-remitting multiple sclerosis. Several prior case reports have demonstrated colitis in association with ocrelizumab infusion, and one case report has shown ocrelizumab-associated diverticulitis. We report on two cases in which ocrelizumab treatment of multiple sclerosis was complicated by acute diverticulitis. A 50-year-old woman and a 41-year-old man, both with relapsing-remitting multiple sclerosis, presented with acute abdominal pain. One patient had no known gastrointestinal history while the other had a history of laparoscopic sleeve gastrectomy. Both patients had received an ocrelizumab infusion one month prior to presentation. The woman underwent exploratory laparotomy, which revealed perforated sigmoid diverticulitis. The man was initially suspected of appendicitis and was treated with appendectomy, but a pathology review demonstrated diverticular disease in the appendix. In patients with multiple sclerosis on ocrelizumab, presentation with diverticulitis should include ocrelizumab-induced diverticulitis in the differential diagnosis.