Johns Hopkins Pathology
 
Key Points:
  • Serous Cystic Neoplasms

Mucinous cystic neoplasms and pseudocysts can both produce cystic masses with thick-walled large cysts; however, these two entities can be distinguished from each other if one considers the clinical, gross and microscopic findings. Pseudocysts are more common in men than in women and the patients typically have a history of pancreatitis and elevated serum amylase levels. By contrast, mucinous cystic neoplasms are more common in women than in men, most of the patients do not develop pancreatitis, and these patients usually have normal serum amylase levels. Most pseudocysts are unilocular and actually extrapancreatic, while most mucinous cystic neoplasms are multilocular and involve the body/tail of the gland. Pseudocysts contain necrotic/hemorrhagic debris with high amylase levels, while the cysts of mucinous cystic neoplasms contain tenacious mucoid material with amylase levels equal to or lower than the patient's serum amylase level. Microscopically pseudocysts will lack an epithelial lining, while mucinous cystic neoplasms will be lined by columnar mucin-containing epithelial cells. Finally, even when the epithelium of a mucinous cystic neoplasm is partially denuded, the presence of ovarian-type stroma will help separate mucinous cystic neoplasms from pseudocysts.

Mucinous cystic neoplasms also need to be distinguished from intraductal papillary neoplasms. IPMN's occur more often in men than in women and tend to involve the head of the gland more frequently than the tail of the gland. By contrast, mucinous cystic neoplasms occur much more commonly in women, and involve the body/tail more frequently than the head of the gland. IPMN's, by definition, involve a larger pancreatic duct, while the cysts in vast majority of mucinous cystic neoplasms do not communicate with the larger ducts. Microscopically, the cysts of both neoplasms will be lined by columnar mucinous epithelium, but only mucinous cystic neoplasms will have the dense ovarian type stroma.

It is important to distinguish between mucinous and serous cystic neoplasms because almost all serous cystadenomas are benign, while mucinous cystic neoplasms have a significant malignant potential. The smaller size of the cysts, central stellate scar and low cuboidal lining make it easy to distinguish most serous cystadenomas from mucinous cystic neoplasms. Oligocystic serous cystadenomas, because they are composed of only a few larger cysts, can mimic mucinous cystic neoplasms, the cyst contents, epithelial lining and the strom can help distinguish between these two entities.

Both solid-pseudopapillary tumors and mucinous cystic neoplasms occur much more commonly in women than they do in men. Both of these entities should therefore be near the top of the differential diagnosis of cystic neoplasms in women. It is relatively easy to distinguish between these two entities. The spaces in solid-pseudopapillary tumors are not true cysts; instead they are areas of necrosis and hemorrhage with drop-out of the neoplastic cells. By contrast, the cysts in mucinous cystic neoplasms will be filled with thick tenacious mucoid material. Microscopically, solid-pseudopapillary tumors are composed of relatively uniform cells with granular eosinophilic cytoplasm and uniform oval nuclei. Mucinous cystic neoplasms are line by a well-oriented layer of mucin comatining columnar epithelial cells. Mucinous cystic neoplasms will express carcinoembryonic antigen and MUC5AC, while solid-pseudopapillary tumors will express CD 10 and vimentin, alph-1-antitrypsin, and show an abnormal nuclear accumulation of beta-catenin.

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