Parvovirus B19 infection preceding the diagnosis of childhood myelodysplastic syndrome with low blasts: a case report.

Parvovirus B19 (PVB19) infection is a recognized cause of transient bone marrow suppression and pure red cell aplasia; however, pancytopenia with hypocellular marrow and multilineage dysplasia is uncommon in children and poses a diagnostic challenge. We report the case of a previously healthy 7-year-old girl who presented with pancytopenia during acute PVB19 infection, confirmed by high viral loads in peripheral blood, cerebrospinal fluid, and bone marrow. Initial bone marrow examination demonstrated hypocellularity with multilineage dysplasia but did not meet criteria for myelodysplastic syndrome. Comprehensive evaluation excluded autoimmune disease, primary immunodeficiency, inherited bone marrow failure syndromes, and known pediatric MDS predisposition genes. Serial follow-up revealed persistent hypocellularity and evolving dysplasia, ultimately establishing the diagnosis of childhood MDS with low blasts (cMDS-LB). The patient underwent successful allogeneic hematopoietic stem cell transplantation with stable full donor chimerism and hematologic recovery. Post-transplant, she experienced episodes of febrile pneumonitis accompanied by transient increases in PVB19 DNA levels, followed by a gradual decline with persistent low-level PVB19 DNAemia at last follow-up (day +618). This case highlights that PVB19 infection may temporally coincide with, reveal, or contribute to an evolving pediatric myelodysplastic process rather than directly causing it.