Classifying non-Hodgkin lymphoma (NHL) can be quite confusing (even for doctors) because there are so many types and because several different systems have been used. The most recent system is the World Health Organization (WHO) classification. The simultaneous occurence of lung cancer without mediastinal lymphoadenopaties and malignant lymphoma involving intrathoracic lymph nodes, to the best of our knowledge has never been previously reported in literature. Collision tumors represent a very rare entity, most of the times diagnosed at the onset of presentation. The diagnostic criteria for Multiple Primary Cancer (MPC), as defined by Warren and gates , include the following conditions: 1) each neoplasm must show specific malignant findings. 2) each lesion must be separate and distinct in site; 3) the possibility that one neoplasm represent a metastatic focus from the other should be excluded.