The 5th edition of World Health Organization Classification of Haematolymphoid Tumours (WHO-HAEM5) is characterized by its hierarchical system for classification and novel entities/types. Considering the significant discrepancy in clinical manifestations and prognosis, fluid overload-associated large B-cell lymphoma (FOALBCL) has been a new addition to the WHO-HAEM5, being distinct from the traditional diagnosis of primary effusion lymphoma. In this manuscript, we report a patient who was diagnosed with FOALBCL that a novel entity introduced in the WHO-HAEM5. It is an instance of a successful application of the updated WHO-HAEM5 and indicates that the 'Blue Book' could confer convenience and benefits on both patients and clinicians. Moreover, the patient combined primary biliary cirrhosis (PBC), which is a relatively rare condition compared to the underlying medical condition of viral cirrhosis. Due to atypical clinical symptoms and invasive biopsy of lymphoma, sometimes, diagnoses might be undesired, which eventually leads to a poor prognosis. With this case report, it reminds not just hematologists but also other specialists to pay attention to the updates and revisions of the classifications of lymphoma.