Pancreatic mucinous cystic neoplasm

Cystic pancreatic neoplasms consist of a heterogeneous group of pathologic entities, which share only cystic appearance on abdominal imaging and a predilection for female gender.

Most common cystic pancreatic neoplasms are mucinous cystic neoplasms and serous cystadenomas.

These two entities account for more than 75% of the cystic pancreatic neoplasms.

Other cystic pancreatic neoplasms include papillary cystic tumors, cystic neuroendocrine tumor, cystic teratoma, lymphangioma, hemangioma, and paraganglioma.

Mucinous cystadenomas are the most frequent cystic tumors of the pancreas and comprise approximately 50% of all cystic tumors.

Mucinous cystic neoplasms of the pancreas comprise about 25% of all resected cystic neoplasms of the pancreas.

These tumors are usually benign, but the majority if left untreated will probably evolve to a malignant tumor.

Eighty percent of MCNs occur in women.

Mean age at presentation of 54 years.

Most frequent presenting symptoms include abdominal pain, weight loss, early satiety, and nausea and vomiting.

Twenty percent of MCNs and 50% of serous cystadenomas are asymptomatic and are discovered incidentally during laparotomy or radiological evaluation performed for an unrelated problem.

Most MCNs consist of large cysts filled with thick mucoid material.

The cyst walls are dense and fibrous and may even be calcified.

Mucin-producing epithelial cells line the cyst, and large areas of denudation of the epithelium is common.

Cystic tumors of the pancreas are distinguished from pseudo-cysts by the presence of solid components, septa, and loculations on CT scan and ultrasonound.

Calcifications can be seen in one third of cystic tumors.

The presence of peripheral calcifications within the tumor is pathognomonic for mucinous cyst and is a marker of increased malignant risk.

Misdiagnosis of a cystic neoplasm as a pancreatic pseudocyst either delays appropriate resection or leads to performance of an inappropriate porceure.

Unlike pseudocysts neoplastic cysts arise de novo without preceding pancreatitis.

Rarely can can cause acute pancreatitis due to obstruction of the pancreatic duct.

Elevated serum amylase supports the diagnosis of a pseudocyst, and a normal value provides no diagnostic information.

Cysts whose fluid is low in amylase are almost always neoplastic.

The diagnostic accuracy of cytology obtained by CT-guided aspiration has an overall accuracy is 67% for malignant cysts and 40% for mucinous cysts.

MRI more effective than CT scan in predicting the diagnosis of MCN.

Analysis of cystic fluid can distinguish between mucinous cyst neoplasms and serous cystic neoplasms.

Fluid in MCNs is more viscous than within serous cystadenomas.

Carcinoembryonic antigen appears is the best marker for detecting MCNs.

Endoscopic ultrasound can differentiate benign cystic lesions from malignant ones according to the wall and septa characteristics.

Nonneoplastic tumors belonged to the thin septa type or simple type, and all malignant tumors have thick walls.

The accuracy of endoscopic ultrasound for differentiating tumors, is estimated at greater than 90%

EUS was significantly superior to ultrasonography, CT, and ERCP for the detection of mural nodules, and such nodules suggests malignancy in both cystic tumor types.

EUS therefore facilitates the diagnosis and allows sampling of cystic fluid material for analysis and evaluation of the mucins and tumor markers.

Positive cytology in cystic fluid, or an elevated level of a tumor marker had an accuracy of 86%, a sensitivity of 83%, a specificity of 88%, a positive predictive value of 83%, and a negative predictive value of 88% for diagnosing a cystic neoplasm.

MCNs histologically characterized by cysts lined by columnar mucin-producing cells surrounded by spindle ovarian-stroma, which is estrogen receptoe and progesterone positive

Typically MCNs do not involve the main pancreatic duct.

Malignant potential includes a larger size, and a solid component.

MCNs should be resected according to standard oncologic principles.

All MCNs considered malignant or premalignant should be resected..

Completely resected MCNs have a 5-year survival rate of more than 50% reported for malignant lesions.

Long-term survival is possible in patients with cystadenocarcinomas, so these patients should undergo resection with the intent to cure even if a large tumor or local extension is found.

Thr prognosis for those with distant spread is similar to patients with ductal adenocarcinoma.

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