Coexisting Waldenström macroglobulinaemia and alveolar echinococcosis presenting with chylothorax that resolved on treatment: a diagnostic and therapeutic challenge

Introduction: Waldenström macroglobulinaemia is a lymphoplasmacytic lymphoma producing monoclonal immunoglobulin M (IgM), and both the disease and its treatment can cause immunosuppression. Alveolar echinococcosis is a parasitic infection that primarily involves the liver but may present with extrahepatic manifestations. Case description: We report the case of a patient who presented with chylothorax and non-specific hepatic lesions and was then diagnosed with Waldenström macroglobulinaemia. In addition to this diagnosis, alveolar echinococcosis was subsequently confirmed by liver biopsy and serology. Discussion: Diagnostic interpretation was challenging, as these features may occur in both conditions. A multidisciplinary approach was needed to establish the treatment plan due to overlapping symptomatology and the risk of treatment-related immunosuppression. Conclusion: This case highlights the importance of considering a broad differential diagnosis for a chylothorax and hepatic lesions in an oncological context and illustrates the therapeutic challenges of managing an indolent haematologic malignancy in the context of a chronic parasitic infection. LEARNING POINTS: Chylothorax has a large differential diagnosis and is often difficult to treat.Echinococcosis can clinically and radiologically mimic malignancy.The investigation and management of a patient with both conditions are challenging.