Serous cystadenoma of the pancreas with invasive growth: benign or malignant?

We describe a case of serous cystadenoma, that invaded a lymph node and adipose tissue. Preoperatively, the cystic lesion of the pancreas was diagnosed as a serous cystadenoma and subsequently the patient, a 71-yr-old woman, underwent distal pancreatectomy with splenectomy. Macroscopically, a greyish white, externally lobulated and partly ovoid tumor, measuring 12 x 8.5 x 5 cm, occupied the pancreatic body and tail extensively. In cross-section, multiple nodules were observed, which measured from 0.5 to 3 cm in diameter, were separated by hyalinized fibrous septa and were filled with numerous microcysts. Light microscopic findings were consistent with those for serous cystadenoma. At the splenic hilus, the tumor was found to have invaded the lymph node and adipose tissue. Based on the clinicopathological features of the six reported cases, including the present case (which behaved in a malignant fashion in terms of pathological findings of invasion or metastasis), serous cystadenoma should be regarded as having the potential for malignant growth.