“…The syndrome of inappropriate antidiuretic hormone has been reported in conjunction with many types of cancer, most frequently in association with small cell lung carcinoma. [6][7][8] Because of the common linkage between LE, SIADH, and cancer, a thorough workup for malignancy needs to be initiated in any patient with subacute memory impairment, seizures, and hyponatremia. We discuss the case of a patient with this type of presentation who was ultimately found to have SIADH due to ectopic antidiuretic hormone (ADH) production by a neuroendocrine tumor with a Merkel cell carcinoma (MCC) immunophenotype.…”