Cystic pancreatic neuroendocrine tumors (cP-NET) are a diagnostic challenge for clinic, since sometimes nor imaging features, cytology, or the study of biological markers in pancreatic cyst fluid (PCF), are able to provide the nature of the lesion, and therefore the definitive diagnostic is often made in the surgical piece. Is not infrequent that the lesions are wrongly defined as benign, in special when the cytology is negative for malignancy and the PCL is not mucinous and has a high glucose and a low CEA. We could incorporate new markers to improve the diagnostic performance of PCF samples, like chromogranin A, as in our case may be the only specific finding to detect a cP-TNE.