Intravascular Large B-cell Lymphoma Presenting as Progressive Cholestatic Liver Dysfunction and Multiorgan Failure Initially Mimicking Acute Calculous Cholecystitis: A Case Report.

Intravascular large B-cell lymphoma (IVLBCL) is a rare and aggressive subtype of extranodal diffuse large B-cell lymphoma characterised by selective proliferation of neoplastic lymphocytes within the lumina of small blood vessels. The disease often presents with nonspecific constitutional symptoms and can involve multiple organ systems, making diagnosis challenging and frequently delayed. We report the case of a 71-year-old man who presented with recurrent chest infections, significant unintentional weight loss, and abnormal liver function tests. Initial imaging performed as part of a malignancy workup suggested acute calculous cholecystitis, leading to surgical admission. Subsequent magnetic resonance cholangiopancreatography (MRCP) demonstrated no imaging evidence supporting cholecystitis but revealed hepatosplenomegaly and periportal lymphadenopathy. Despite broad-spectrum antimicrobial therapy and extensive investigation for infectious, autoimmune, and metabolic liver disease, the patient's condition progressively deteriorated, with worsening cholestatic liver dysfunction, hypoxemic respiratory failure, acute kidney injury requiring continuous renal replacement therapy, and eventual multiorgan failure. Due to persistent diagnostic uncertainty and ongoing clinical decline, an image-guided liver biopsy was performed. Histopathological analysis demonstrated intrahepatic IVLBCL. Following multidisciplinary discussion, treatment with high-dose methylprednisolone was initiated with the intention of proceeding to rituximab-based chemotherapy. However, the patient's clinical condition continued to deteriorate rapidly, precluding definitive chemotherapy. Following discussions regarding goals of care, palliative management was pursued, and the patient subsequently died in intensive care. This case highlights the diagnostic challenges associated with IVLBCL and emphasises the importance of considering an early biopsy, as this rare entity may rapidly progress to multiorgan failure if diagnosis is delayed.