Abstract
Mantle cell lymphoma (MCL) is a rare type of B cell non-Hodgkin's lymphoma. MCL is most commonly identified in the gastrointestinal tract. Yet, many other extranodal sites have been described in the literature, including the rare instances of the primary site being the pleura of the lung. We present a case with a 73-year-old female who presented with a three-month history of unintentional weight loss, nocturnal fever, and night sweats. She had recurrent left pleural effusions; however, thoracentesis and pleural fluid cytology were negative for malignancy. A definitive diagnosis was achieved after the patient underwent video-assisted thoracic surgery. MCL presenting as a pleural effusion is rarely reported in the literature.