Parvovirus B19-Associated Hematological Complications: Two Case Scenarios of Pure Red Cell Aplasia and Hemophagocytic Lymphohistiocytosis.

Parvovirus B19 (PVB19) has tropism for erythroid precursors and may cause clinically important hematological syndromes, including pure red cell aplasia (PRCA). Less commonly, it may be associated with secondary hemophagocytic lymphohistiocytosis (HLH). We report two PVB19-associated hematological presentations identified through bone marrow morphology. Case 1 was a 60-year-old woman with severe anemia, reticulocytopenia, and bone marrow erythroid hypoplasia. Giant pronormoblasts prompted PVB19 testing, and anti-PVB19 IgM was positive, consistent with PVB19-associated PRCA. Case 2 was a two-year-old girl with prolonged fever, hepatosplenomegaly, edema, ascites, and pancytopenia. Bone marrow examination showed hemophagocytosis and erythroid precursors with cytoplasmic blebs/pseudopodia. Hyperferritinemia and hypofibrinogenemia supported an HLH phenotype, and anti-PVB19 IgM was positive. Both patients received supportive care with corticosteroid-based immunomodulation; intravenous immunoglobulin was used as part of management. Hematological recovery was documented during follow-up. PVB19 should be considered in unexplained cytopenias when marrow morphology shows giant pronormoblasts, erythroid hypoplasia, or suggestive erythroid viral cytopathic changes. Early recognition may direct timely etiologic confirmation and individualized supportive or immunomodulatory treatment.