Macrocystic serous cystadenoma of the pancreas: importance of co-existent tiny cysts depicted by EUS.

The case of a 38-year-old man with an unusual type of serous cystadenoma of the pancreas is reported. A multilocular cystic tumor in the head of the pancreas was detected on abdominal ultrasonography and computed tomography. On endoscopic ultrasonography, the major cysts ranged from 2.0 to 4.5 cm in size. In addition to these large cysts, a few small cysts were detected. Based on these findings, this tumor was diagnosed as a macrocystic type serous cystadenoma. Because endoscopic retrograde pancreatogram showed a compression of the main pancreatic duct around the tumor, and because the size of the tumor had been increasing over a 3-year period, surgical intervention was performed. The resected tumor consisted of macrocysts, with a few small cysts, and was histologically diagnosed as serous cystadenoma. Endoscopic ultrasonography appears to provide an excellent inside image of this unusual tumor, and because of its ability to detect small cystic lesions clearly, it could be useful in the diagnosis of macrocystic serous cystadenoma.