Disseminated human parvovirus B19 encephalitis and pure red cell aplasia unmasking immune dysregulation in angioimmunoblastic T-cell lymphoma

BACKGROUND: Acute encephalitis caused by human parvovirus B19 (PVB19) is an uncommon clinical manifestation observed in both immunocompetent and immunocompromised individuals. Angioimmunoblastic T-cell lymphoma (AITL) is a distinct subtype of lymphoma characterized by aberrant immune dysregulation, predisposing patients to opportunistic infections even in the absence of chemotherapy. CASE PRESENTATION: A 66-year-old woman with newly diagnosed, treatment-naïve AITL presented with acute confusion, dysarthria, and severe anemia. Cerebrospinal fluid (CSF) analysis and neuroimaging findings were non-specific. PVB19 DNA was subsequently detected in both the CSF and serum. A bone marrow biopsy confirmed PVB19-associated pure red cell aplasia (PRCA). Intravenous immunoglobulin therapy resulted in a declining viral load and clinical improvement. The patient's clinical course was complicated by multiple subsequent infections, and she ultimately died five months after discharge. CONCLUSION: This case highlights the immunodeficiency caused by AITL, which predisposes patients to opportunistic infections. PVB19 infection should be considered for patients presenting with unexplained encephalitis, particularly in those with underlying immunocompromised conditions.