The mucinous type of cystadenoma of the pancreas is known to have malignant potential, whereas the serous type is believed to be benign. Therefore, the therapeutic strategies for serous cystadenomas are less aggressive than in mucinous cystadenoma, where complete operative resection is the procedure of choice. A patient with a biopsy-proven serous cystadenocarcinoma with a lymph node metastasis is reported. Considering the reported case and a review of the literature, the origin of serous cystadenocarcinoma appears to be from cystadenoma lesions. Even if this development of cystadenocarcinoma in pre-existing serous cystadenoma lesions is a rare entity, a less aggressive treatment of this lesion should be avoided in favor of resection procedures because of the good chance of cure.