Late-Onset Veno-Occlusive Disease (VOD) Post-Haploidentical Transplant: A Diagnostic Challenge Requiring Liver Biopsy– A Case Report

Background: Veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS) is a potentially fatal complication post-hematopoietic stem cell transplantation (HSCT), classically presenting within the first 3 weeks. However, late-onset VOD, often presenting beyond day +21, may lack the classical hallmarks, making diagnosis particularly challenging. Case Presentation: We report a 41-year-old female with adverse-risk acute myeloid leukemia (AML) who underwent haploidentical HSCT in first complete remission. On day +35, she developed hemorrhagic cystitis due to BK polyomavirus and CMV viremia, followed by progressive abdominal distension, hepatomegaly, ascites, and mild hyperbilirubinemia. Initial imaging and laboratory investigations were non-specific. A diagnostic transjugular liver biopsy performed on day +52 revealed classical features of SOS with zone 3 perisinusoidal fibrosis. She was managed conservatively with complete clinical resolution. Conclusion: This case highlights the diagnostic complexity of late-onset VOD and reinforces the indispensable role of liver biopsy when conventional criteria are inconclusive.