Johns Hopkins Pathology

 
Key Points:
  • Body or tail of pancreas
  • Multilocular
  • No communication with ducts
Images: Mucinous cystadenoma | Mucinous cystadenocarcinoma | Probe in duct |

The majority (70-90%) of mucinous cystic neoplasms arise in the body or tail of the pancreas, and only a minority (10-30%) involve the head of the gland. Mucinous cystadenocarcinomas involve the head of the gland slightly more often than do mucinous cystadenomas. Mucinous cystic neoplasms are usually quite large (2-35 cm, mean ~7 to 10 cm), and mucinous cystadenocarcinomas tend to be even larger.

On cut section mucinous cystic neoplasms are usually multilocular, but an occasional tumor can be unilocular, a feature that can mimic a pseudocyst. The cysts are typically between 1 and 3 cm, but cysts as small as a few millimeters and as large as 23 cm have been reported. The cysts have a thick-wall and are filled with thick tenacious mucoid material. The lining of the cysts can be smooth, particularly in benign mucinous cystic neoplasms, or there can be intracystic papillary excrescences (projections) and even solid mural nodules; features that suggest the diagnosis of a mucinous cystadenocarcinoma. Focal calcifications are sometimes present in the periphery of the tumors. Only a small minority (~5%) communicate with the larger pancreatic ducts.

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