Parvovirus B19-induced aplastic anemia following mechanical valve replacement.

Human parvovirus B19 infection in immunocompetent adults predominantly manifests as arthropathy or erythema infectiosum, with transient aplastic crisis being a rare hematological complication. We report a diagnostically challenging case of a man in his late 40s who developed recurrent severe aplastic anemia following mechanical valve replacement. Notably, the patient presented with progressive pancytopenia despite optimal anticoagulation and normally functioning prosthetic valves on serial echocardiograms. Critical diagnostic differentiation was achieved through comprehensive laboratory evaluation; elevated lactate dehydrogenase (232.00 U/L) and undetectable haptoglobin levels initially suggested mechanical hemolysis. However, suppressed reticulocyte production index (0.002) and the presence of human parvovirus B19 (DNA) confirmed virus-mediated marrow suppression. The absence of schistocytes on peripheral smear and stable hemoglobinuria levels further excluded prosthetic valve-related hemolysis. To the best of our knowledge, this study represents the first documented case of human parvovirus B19-induced aplastic anemia in a postcardiotomy patient with confirmed valve competence, highlighting three key clinical imperatives: 1. Human parvovirus B19 should be included in the differential diagnosis of postoperative pancytopenia regardless of immune status; 2. disproportionate reticulocytopenia with normal hemolysis markers may indicate viral marrow infiltration; and 3. serial echocardiographic surveillance cannot fully exclude subclinical hemolysis, necessitating multimodal laboratory correlation.