The authors present the case of a lymphoproliferative disorder (LPD) with pleuro-pulmonary involvement. It was a very aggressive primary gastric lymphoma of the MALT subtype, diagnosed in an 86-year-old woman admitted in Pulmonology ward at our Hospital with pleural effusion. Helicobacter pylori search was negative, what is infrequent. The disease was already disseminated at the time of the diagnosis and did not respond to various treatment modalities, what is also an uncommon finding. Clinical presentation, diagnosis and management of this disease are reviewed, pointing out its unique features and comparing the particular aspects of this case with the published literature. The authors stress that LPD is an important diagnosis to be held in mind in the case of a pleural effusion of unknown aetiology.