Case Report: From complete remission to severe anemia: pure red cell aplasia emerged after VRd regimen in multiple myeloma.

Pure red cell aplasia (PRCA) is a rare disorder characterized by severe reticulocytopenia and absence of erythroid precursors. Its association with multiple myeloma (MM) therapy is uncommon. We report a 73-year-old man with MM (IgGλ, stage IIIA) who achieved complete remission after five cycles of VRd (bortezomib, lenalidomide, dexamethasone). During lenalidomide maintenance, he developed severe anemia (hemoglobin 45 g/L, reticulocytes 0.01%). Bone marrow biopsy showed absent erythroid precursors with preserved granulocytic and megakaryocytic lineages, consistent with PRCA. Following discontinuation of lenalidomide, cyclosporine therapy increased hemoglobin to 92 g/L within one month. This case highlights that PRCA can occur after MM treatment and underscores the importance of early detection by monitoring reticulocytes. A comprehensive approach including withdrawal of offending agents and immunosuppressive therapy is critical.