Rheumatoid arthritis is the one of the most prevalent inflammatory chronic joint diseases. The RA is associated with other diseases and its complication can be attributed to other causes. Therefore, it is important to keep in mind all the possible manifestations of the disease to give an accurate diagnosis and treatment. This case report presents a 61-year-old man with a previous history of rheumatoid arthritis who attended the emergency department due to constitutional symptoms, dyspnea and the appearance of lymphadenopathy, and a mass in the right iliac fossa. During his hospitalization, a diagnosis of nongerminal center diffuse B-cell lymphoma was made and a thoracoabdominal computed tomography showed the presence of an extensive pleural effusion in the right hemithorax. Therapeutic thoracentesis was performed with findings of cholesterol crystals. In addition, the cytochemical study of the fluid was compatible with a pseudo chylothorax. Lately to exclude other possible causes such as neoplastic, infectious, and metabolic causes, it was determined that the pleural effusion was consequence of pleurodesis as an extrapulmonary manifestation of RA. The patient was managed with steroids with resolution of the pleural effusion and hospital discharge.