The pathological diagnosis of lung cancer is based on the WHO classification 2004. Tumors containing several tumoral contingents are rare but put at the same time problems of diagnosis and therapeutic coverage. On biopsy, the diagnosis can be refined by using immuno-histochemistry and the recent multidisciplinary classification IALSC/ARS/ETS. Some of these tumors can present molecular anomalies and therefore are accessible to targeted therapies: the precision of the pathological diagnosis is thus essential.