We present a case with gigantic carcinosarcoma (the largest described to date, diameter of 20.5 cm), located in the right upper lobe, in which the discordance between the brief clinical course with limited symptoms and its large size were remarkable. Preoperative diagnosis by bronchial biopsy, as used to be the case in this malignancy, was incorrect (epidermoid), and the define histological characterization was made by thoracotomy. The controversy about pathology, diagnosis and treatment of the carcinosarcoma is discussed.