2024 Volume 63 Issue 5 Pages 249-256
Background : Primary effusion lymphoma (PEL) is a rare B-cell lymphoma that is most often encountered in patients with human immunodeficiency virus infection. On the other hand, several cases of effusion-based lymphoma in Japan have been reported as being HHV-8-negative, leading to their classification as PEL-like lymphomas. Recently PEL-like lymphoma was recognized as an independent disease and named fluid overload-associated large B cell lymphoma (FO-LBCL).
Cases : Case 1. A man in his 70 s was admitted for worsening heart failure. Imaging studies showed massive pericardial effusion, but no mass lesions. Case 2. A man in his 70 s who had undergone surgery for lung cancer was admitted for heart failure. Pleural effusion was detected. Pericardial and pleural effusion cytology in the two cases, respectively, showed a large number of atypical cells. The cells showed weakly basophilic cytoplasm, marked nuclear atypia, and pleomorphism. Scattered giant cells with lobulated nuclei were observed. Immunocytochemical analysis of a cell block showed positive staining for CD20 and CD79a. Based on the findings, the patients were diagnosed as having diffuse large B cell malignant lymphoma. Enhanced CT showed neither tumor masses nor enlarged lymph nodes and the results of tests for HHV-8 and EBER-ISH were negative. Therefore, the patients were diagnosed as having FO-LBCL.
Conclusion : When cells suspicious for malignant lymphoma are found in body fluid, closer examination is necessary, including to rule out the possibility of PEL or FO-LBCL and secondary infiltration at other sites. Immunostaining and genetic analysis are essential for a definitive diagnosis.
