Small cell lung cancer is the most common cause of paraneoplastic Cushing's syndrome. The definitive treatment consists in surgical removal of the tumour, which is not possible in most of these cases (they are often diagnosed at advanced stages), and therefore it is frequently necessary adding the drug ketoconazol. We hereby present the case of a patient diagnosed with a metastatic carcinoma of unknown origin associated with two paraneoplastic syndromes: a Cushing's syndrome and a sensitive-motor axonal neuropathy, a very uncommon association.