Background: Lymphoid neoplasms in serous effusions (SEs) were uncommon. Currently, most reports of lymphoid neoplasms in SEs were from Western countries, but few reports were from China, and the details were still unclear. Methods: Between January 2004 and December 2019, lymphoid neoplasms diagnosed by cytological methods from specimens of pleural effusions (PEs), ascites, and pericardial effusions in our hospital were reviewed.Results: 59 patients of lymphoid neoplasms were diagnosed by SEs, the top three causes were diffuse large B-cell lymphoma (DLBCL) (n=21, 35.6%), myeloma (n=13, 22.0%), and T-lymphoblastic lymphoma (n=5, 8.5%). In PEs involved with DLBCL, the cytomorphology of DLBCL cells was variable, most PEs were present during tumor course (92.9%), bilateral PEs were the predominance (57.2%), and the median survival time was only 1.23 months after effusion. In PEs involved with myeloma, nearly all cases had a high ratio of immature to mature plasma cells (>1.0), IgA (36.4%) and light chain λ (36.4%) were the most frequently found. Bilateral PEs were easily found (90.9%), and the median survival time was only 1.4 months after effusion. Solitary plasmacytomas with myeloma infiltration in PEs seemed to have a better prognosis than that of plasma cell myeloma.Conclusion: Some differences are found between our patients and those from Western countries, and more studies involving different ethnic populations could help to elucidate the features of lymphoid neoplasms in SEs.

Background: Lymphoid neoplasms in serous effusions are uncommon, and the details of lymphoid neoplasms in serous effusions from China are still unclear. Methods: Between January 2004 and December 2019, all patients with lymphoid neoplasms in pleural effusions, ascites, and pericardial effusions in our hospital, were reviewed. Results: A total of 65 patients with lymphoid neoplasms were collected during this period. The top three neoplasms were diffuse large B-cell lymphoma (DLBCL) (n = 20, 30.7%), myeloma (n = 13, 20.0%), and T-lymphoblastic lymphoma (n = 7, 10.8%). In pleural effusions involving DLBCL, the cytomorphology of DLBCL cells was diverse; most pleural effusions were present during the tumor course (92.9%); bilateral pleural effusions were predominant (57.2%); and the median survival time was only 1.23 months after the effusion. In pleural effusions involving myeloma, 90.9% of cases (10/11) had a high ratio (> 1.0) of immature to mature plasma cells; paraprotein types of IgA (36.4%) and light chain λ (36.4%) were the most frequently found; bilateral pleural effusions were easily found (n = 10, 90.9%); and the median survival time was only 1.4 months after the effusion. Conclusion: In pleural effusions involving DLBCL, most of our patients with effusions are present during the tumor course, and bilateral pleural effusions are predominant. In pleural effusions involving myeloma, the paraprotein types of IgA and light chain λ are the most frequently found, and it has a high ratio of immature to mature plasma cells in pleural effusions.