Human parvovirus B19-associated Evans syndrome with fulminant hematologic onset mimicking thrombotic thrombocytopenic purpura: a case report

Abstract Background Human parvovirus B19 infection rarely presents with severe bicytopenia and multiorgan involvement. Acute presentations with fulminant immune-mediated cytopenia closely mimic severe thrombotic microangiopathies (TMAs) like thrombotic thrombocytopenic purpura (TTP), making early diagnosis highly challenging. Case presentation A 65-year-old male was admitted with hematemesis and melena. Suspecting thrombotic thrombocytopenic purpura or other thrombotic microangiopathies, emergency plasma exchange and continuous renal replacement therapy were immediately initiated. Crucially, pre-treatment samples for ADAMTS13 and metagenomic next-generation sequencing were collected prior to these interventions. Following rapid clinical deterioration requiring endotracheal intubation, intravenous methylprednisolone was initiated. Initial platelet and hemoglobin levels were 3×10⁹/L and 90 g/L, which subsequently plummeted to nadirs of 1×10⁹/L and 46 g/L. Immunohematological tests identified immune-mediated cytopenia: a weakly positive direct antiglobulin test for IgG, positive C3, and spherocytes. ADAMTS13 activity was normal. The pre-treatment metagenomic next-generation sequencing exclusively detected parvovirus B19 (21632 reads), shifting the diagnostic focus to B19-associated Evans syndrome. Following comprehensive therapy, the patient demonstrated a progressive regenerative erythropoietic response. He was successfully extubated, with platelets recovering to 174×10⁹/L and hemoglobin to 86-87 g/L. Conclusions Parvovirus B19 should be actively considered in adults presenting with fulminant immune-mediated bicytopenia mimicking TTP. Procuring critical etiological and immunohematological samples prior to plasma exchange is essential to establish an accurate final diagnosis.