ABCL-087: Lymphocytic Pleural Effusion: An Unusual Initial and Isolated Presentation of Non-Hodgkin Lymphoma

Abstract

Pleural involvement from diffuse large B-cell lymphoma (DLBCL) has been reported in the literature, and it is associated with poor outcome. However, non-Hodgkin lymphoma presenting as an isolated pleural effusion is unusual. Here we report the case of 84-year-old female patient, without past medical history, who presented for worsening shortness of breath. Investigations were pertinent for a left pleural effusion without other clinically significant findings in the laboratory and radiological work-up. A left pleural thoracentesis showed a lymphocytic exudative effusion. The complete screening for fungal or bacterial etiologies, including mycobacterium tuberculosis, was negative. The cytology didn't reveal any abnormal or malignant cells. Unfortunately, the effusion worsened 48 hours after the prior pleural tap. We repeated the thoracentesis, and we were able to obtain a cell block. Microscopic evaluation and immunohistochemistry were relevant for numerous intermediate to large-sized tumor cells with round nuclei; they stained positive for CD20, multiple myeloma-1 (MUM1), B-cell chronic lymphocytic leukemia/lymphoma (Bcl6), Bcl2, and negative for CD3, CD138, CD10. The Ki67 was 95%. Thus, she was diagnosed with DLBCL involving the left pleura. 18-fluorodeoxyglucose (FDG) PET-CT scan showed an isolated hypermetabolic left pleural effusion without any other nodal or skeletal uptake. Bone marrow biopsy was negative for any lymphomatous infiltration. Taking into consideration her age, she was started on R-mini-CHOP chemotherapy protocol with drastic improvement of the pleural effusion after the first session. She completed 6 cycles of R-mini-CHOP with primary G-CSF prophylaxis and is currently in complete remission. Although it is a rare entity, isolated pleural DLBCL should be considered whenever we have a non-resolving lymphocytic pleural effusion. Clinicians and pathologists must be aware of this diagnosis which is made by cytopathology, immunohistochemistry, and flow cytometry on pleural fluid.