[Pure red cell aplasia in a patient with cold agglutinin disease-associated lymphoproliferative disorder].

A 51-year-old woman had been noted to have anemia since 2019 and developed Raynaud's phenomenon during winter or in air-conditioned environments from 2021. In January 2024, she experienced palpitations, tinnitus, dyspnea on exertion, and fatigue. Twenty-three days later, she was urgently admitted to hospital with severe anemia (Hb 2.8 g/dl). She was diagnosed with primary cold agglutinin disease (CAD) and CAD-associated lymphoproliferative disorder (LPD). While she was under observation, undergoing red blood cell transfusion with avoidance of cold exposure, her anemia progressed without worsening of hemolysis and she was diagnosed with pure red cell aplasia (PRCA). Cyclosporine A (CsA) was administered for 10 days without response, and treatment was switched to bendamustine-rituximab (BR) for LPD. Although her LPD improved, her PRCA persisted; CsA was therefore resumed, leading to improvement in the PRCA. In October, her CAD-LPD relapsed with hemolysis, and BR therapy with continued CsA treatment again achieved improvement in the CAD-LPD without worsening of the PRCA. This rare case of primary CAD-associated LPD complicated by PRCA highlights the importance of accurate disease assessment and appropriate treatment strategies.