Is the paraneoplastic syndrome of inappropriate antidiuretic hormone secretion in lung cancer always attributable to the small cell variety?

The syndrome of inappropriate antidiuretic hormone (SIADH) secretion is a well recognised paraneoplastic phenomenon and the vast majority are associated with small cell lung carcinoma. Rarely however, the non-small cell variety can sometimes be responsible and this report describes such an occurrence. Uniquely in this case, after chemotherapy the paraneoplastic SIADH improved in parallel with a tumour response and this has not been reported previously.