Pancreas Pathology Research: Serous Cystadenoma And Mucinous Cystic Neoplasms

Abstract

Pancreatic cystic neoplasms demonstrate approximately 15% of all pancreatic tumors. Serous Cystic Neoplasm (SCN) is a benign lesion, and observation is the primary line of treatment before surgical procedures should be used. Mucinous Cystic Neoplasm (MCN) may initially begin as benign, but more likely has a malignant potential and surgical reconstruction is the primary recommended use of treatment. The serous and mucinous pancreatic neoplasm is distinguished prior to the operative procedure and according to their completely different treatment strategies.

Introduction

“Mucinous Cystadenocarcinoma may also be referred to its original name macrocystic adenoma.' 'It can be benign, but has the potential of becoming malignant.”1 “It is rare, slow growing usually in the body or tail of the pancreas.” “It may appear large, cystic, lobulated, irregular thick walls.” “Symptoms include epigastric pain or mass-like appearance.”

“Serous Cystadenoma may as well be referred to its original name microcystic adenoma.” “It is a rare type consisting of tiny cysts with glycogen cells located normally in the body or tail of the pancreas.” “It usually appears as a multilocular mass or have a “cluster of grapes” resemblance.” “This condition is associated with von Hippel-Lindau.”

Serous Cystadenoma

Polycystic Serous Cystadenoma are observed in women around the age 50 and older in about 80-90% of cases.2 Less than 50% of the tumors are asymptomatic for patients and commonly incidental. They may be located in the head, body, or tail in the pancreas, but the most common area is usually the head. Serous Cystadenomas normally do not communicate with the pancreatic ducts. If the pathological cyst communicates with the pancreatic ducts (ampulla of Vater area), then the prognosis is considered abnormally rare. There is a common form of this with a polycystic pattern with multiple cysts measuring less than 2 centimeters diameter in 70% of cases. The cysts are separated by fibrous bands that may create a scar-like structure that later calcify. The normal appearance shows a honeycomb-like pattern. Serous Cystadenomas may also be classified as polycystic, honeycomb, or oligocystic.

Then there is an oligocystic pattern in about 10% of serous pathology cases that is a rare type of form with few, larger cysts that have more than 2 centimeters in diameter. This form also has a honeycomb-like appearance composed of microcysts within another. It is typically a hypoechoic round-shape mass with multiple other hypoechoic small cysts within the structure. If a central scar is visualized it is usually a bright or hyperechoic type of adhesion. When using iodine injection the cysts are highly attenuating with lobulated edges and a fibrous scar is greatly enhanced.

Serous Cystadenoma are rare, slow, growing tumors with rupture occurring in most that are measured more than ten centimeters. Obstructive chronic pancreatitis and compression of the pancreatic ducts may occur. Most Serous Cystadenoma are considered benign, but a small potential develop into malignant forms spreading to the liver (liver metastasis), perineural invasion along the head, neck, prostate, or colorectal area, and vascular invasion where breast cells break into the blood vessels or lymph node channels. Surgery is indicated if they become very large and the patient is symptomatic. However, mucinous cystadenomas may progress into an invasive cystadenocarcinoma. Serous cysts post-operation appear as multiple microcysts with dense, collagen fibers. The walls are covered with a layer of flat, square-like epithelium with nuclei and glycogen inside the cells. Serous cystadenoma may have a sponge-like, hyperechoic mass with posterior acoustic enhancement. Solid pseudopapillary tumors may be difficult to recognize from the serous cystadenoma.

Other Referred Terms

Pancreatic cancer refers to pancreatic ductal adenocarcinoma even though there are other types of exocrine epithelial tumors of the pancreas. There are many terms used interchangeably for the different types of tumors. Benign tumors include serous cystadenoma and hamartoma. Borderline tumors include intraductal papillary mucinous neoplasm and solid pseudopapillary tumor. Malignant tumors include ductal adenocarcinoma, intraductal papillary mucinous carcinoma, mucinous cystadenocarcinoma, signet ring cell carcinoma, adenosquamous carcinoma, anaplastic carcinoma, mixed ductal endocrine carcinoma, osteoclast-like-giant cell tumor, acinar cell carcinoma, and pancreatoblastoma.

Signs/Symptoms

Tobacco smoking is a primary, major risk factor occurring in less than 30% cases and family history in less than 10% of cases is secondary.4 Tumors in the head of the pancreas result in 80% of the time with painless obstructive jaundice with dark urine and pale stools. Symptoms include painless jaundice, pruritus, fatigue, weight loss, back pain when lying down, dyspepsia (abdominal discomfort), anorexia, constipation, steatorrhea (fatty stools), late diabetes mellitus, acute pancreatitis (unknown cause), chronic pancreatitis, acute cholangitis, vomiting from duodenal obstruction, and deep-vein thrombosis. Other signs may include, multiple bruises, hepatomegaly, palpable gallbladder (Courvoisier's sign), cachexia (severe weight loss and muscle loss), anemia, left supraclavicular (Virchow's) node enlargement (Troiser's sign), METS at the umbilicus (Sister Joseph's sign), ascites, venous gangrene of the lower limbs, and migratory thrombophlebitis.

Mucinous Cystadenoma

Mucinous Cysts are usually large, unilocular, septated, thick-walled cysts that lack a communication with the ductal system. These are considered macrocystic lesions (fewer cysts than microcystic lesions, which are larger than 2 centimeters), that are common in middle-aged women and more often located in the tail. Intraductal papillary mucinous neoplasms favor mucinous cystadenomas, but differentiate based on communication with the ductal system.

If an obvious channel of communication with the pancreatic duct is clearly visualized, then the diagnosis is most likely an intraductal papillary mucinous neoplasm. Mucinous Cystadenomas and Serous Cystadenomas do not communicate with the pancreatic ductal system. Mucinous Cystadenomas are asymptomatic, but they can cause pain. They may reveal as a unilocular cyst or few septations of multiple divisions within. Amylase level is usually low because of the non-communication with the pancreatic ductal system. These cysts do have the potential of becoming malignant (Mucinous Cystadenocarcinoma). Since these cysts do occur in younger to middle-aged women, surgical removal of a distal pancreatectomy is the preferred method.

Conclusion

Cancers in the head of pancreas cause dilation of the main pancreatic duct (Duct of Wirsung) and the common bile duct which is called the double-duct sign. Cancers (for example, acinar cell carcinoma) are relatively hypovascular or frequently hypovascular whereas compared to neuroendocrine tumors they are hypervascular. Blood tests will be done for anemia, serous cancer antigen to check for elevations in obstructive jaundice or chronic pancreatitis, abdominal ultrasound for liver METS, and identifying dilated bile ducts or pancreatic ducts. CT/MRI tests may be used to diagnose the patient. Once tests are completed and a diagnosis is identified, an endoscopic treatment may be relieved by a stent placement for the patient with pancreatic cancer. Partial or complete pancreatectomy may also be another option depending on the severity.