Repeated rituximab-induced serum sickness with anaphylaxis.

We describe a patient who developed repeated rituximab-induced serum sickness (RISS) followed by anaphylaxis soon after the third administration of rituximab at relapse. A 65-year-old woman with Sjögren's syndrome and relapsed mucosal associated lymphoma tissue (MALT) lymphoma of the lung underwent rituximab monotherapy (375 mg/m(2)/week). Several days after the second exposure to rituximab, she developed a rash, fever, and arthralgia. These symptoms showed relief, but a severe anaphylactic reaction occurred when she was treated with rituximab for the third time. Although a rare complication in patients with lymphoma, clinicians should be aware of RISS symptoms and avoid repeatedly administering rituximab to such patients.