A case of primary effusion lymphoma-like lymphoma for which a cell block was useful for diagnosis

Abstract

Background: Primary effusion lymphoma (PEL) is a rare malignant lymphoma observed as an effusion in the body cavity without forming any tumor masses and is associated with human herpes virus type 8 (HHV-8) infection. We report a case of PEL-like lymphoma (PEL-LL) observed as a pleural effusion in the absence of HHV-8 infection. A cytology cell block of the pleural effusion was useful for diagnosis. Case: A female in her 90s complained of dyspnea. A chest X-ray examination showed a large amount of bilateral pleural effusion, and thoracic drainage was performed. Pleural effusion cytology showed a large number of atypical cells with large irregular nuclei. Immunocytochemical analysis using a cell block showed CD20, CD79a, and bcl-2 positivities. Therefore, the patient was diagnosed as having diffuse large B cell malignant lymphoma. No tumor mass or lymph node swelling was detected by enhanced computed tomography and no HHV-8 was detected. Therefore, this patient was diagnosed as having PEL-LL. Conclusion: In the present case, the use of a cytology cell block from pleural effusion drained for the first time enabled rapid immunocytochemical analysis, resulting in early diagnosis. Several previous studies have shown that PEL-LL disappeared following effusion drainage. Therefore, constructing a cytology cell block from the initial drained effusions is important for the diagnosis of PEL-LL.