Monoclonal Gammopathy as a Potential Cause of Pure Red Cell Aplasia: A Case Report and Literature Review.

Pure red cell aplasia (PRCA) secondary to plasma cell dyscrasias has been previously reported; however, these cases are rare and often lack clinical details. Here, we report the case of a 44-year-old female patient presenting with progressive normocytic anemia in the setting of an IgG-kappa monoclonal gammopathy, without meeting the diagnostic criteria for multiple myeloma or any other hematological malignancy. Although the initial diagnostic workup for PRCA was inconclusive, and despite a transient response to erythropoiesis-stimulating agents, the condition progressed to severe, transfusion-dependent anemia. PRCA was eventually confirmed and proved refractory to conventional immunosuppressive therapy. Remarkably, plasma cell-directed therapy achieved almost instantaneous normalization of erythropoiesis and rapid paraprotein clearance. This clinical response suggests a pathogenetic role for the monoclonal immunoglobulin. While we were unable to demonstrate an in vitro inhibitory effect of the patient's serum on burst-forming unit-erythroid cultures, our observations, coupled with previously reported cases, support an antibody-mediated mechanism in the pathogenesis of this PRCA variant. We suggest that PRCA associated with monoclonal gammopathy may represent a rare, distinct clinical entity for which plasma cell-targeted therapy could be considered.