BackgroundCold agglutinin disease can lead to significant complications, especially for patients undergoing arch repair requiring hypothermic circulatory arrest. Rituximab and plasmapheresis are treatments for cold agglutinin disease. However, its use in patients with Stanford type A dissection has not been reported. Therefore, after consultation with hematologists, we used rituximab and plasmapheresis before mild hypothermic aortic arch surgery to maintain the body temperature above the thermal altitude.Case presentationThis report describes an 86-year-old male patient with acute type A aortic dissection who received outpatient treatment for rheumatoid arthritis and a 55-mm thoracic aortic aneurysm. The patient was scheduled to undergo urgent surgery for a type A intramural hematoma and progressive aortic aneurysm; however, laboratory test results indicated blood clotting and cold agglutinin. Consequently, urgent surgery was rescheduled. After consulting with hematologists, rituximab was initiated 3 months before surgery, and plasmapheresis was performed 2 days before surgery for cold agglutinin disease. Under mild hypothermia conditions, total arch replacement using the frozen elephant trunk technique was performed while maintaining cerebral and lower body perfusion. The postoperative course was uneventful. On postoperative day 42, the patient was discharged without any neurological deficits.ConclusionsThis case involving total arch replacement with mild hypothermia for an aortic arch aneurysm with cold agglutinin disease after rituximab treatment and plasmapheresis resulted in a successful outcome.