A cystadenoma is a benign growth of glandular tissue that forms a cyst and is filled with secretions. Although cystadenomas are benign, they may cause problems by compressing neighboring tissues. The three major forms are serous, mucinous and papillary cystadenomas. The different forms have varying tendencies for malignant transformation.
Cystadenomas can be found in many tissues, often with a preponderance of one of the three forms (serous, mucinous or papillary). The article below concentrates on cystadenomas of the pancreas, liver, and ovaries. However, a short literature search will discover many other tissues that harbor cystadenomas: among others, the lungs, the appendix, the mesorectum, the epididymis, the spermatic cord, the endometrium, and the parotid gland (papillary cystadenoma of the parotid gland is called Warthin’s tumor).
Most cysts observed in the pancreas are pseudocysts associated with pancreatitis. Cystadenomas are mainly of two kinds: serous and mucinous (called mucinous cystic neoplasm); both occur more frequently in women than men. Intraductal papillary mucinous tumor (IPMT) is a recently recognized category of the latter class. Whereas serous cystadenomas in the pancreas are almost always benign, mucinous cystic neoplasm (MCN) and IPMT can turn malignant - about a third of MCN cases that are resected can be associated with malignant tissue . Patients may present with nausea and abdominal pain, but with the increased use and improvements in radiologic imaging technologies, many cystic lesions are discovered incidentally .
Cysts in the liver are quite common: they occur in 5-10% of the population; however, most of them are simple hepatic cysts. Hepatic (biliary) cystadenomas are much rarer. Biliary cystadenomas are serous and mucinous, with the overwhelming majority belonging to the latter category. Although benign, biliary cystadenomas have a strong tendency to recur, and a high potential for malignant progression. Both cystadenomas and cystadenocarcinomas grow slowly, like simple hepatic cysts. Their presentation – abdominal pain, nausea, and vomiting – is also similar. Many cysts are discovered when imaging is performed for unrelated reasons .
Ovaries may contain a variety of cysts, most of them formed as a result of the normal functioning of the ovaries during the menstrual cycle, such as follicular cysts and corpus luteal cysts. Abnormal growth may lead to the formation of cystadenomas, both serous and mucinous. Serous cystadenomas are the most frequently occurring epithelial ovarian tumors. Mucinous cystadenomas are usually large and multilocular and may have a tendency to grow very large. They may, occasionally, induce excessive accumulation of mucinous material in the abdominal cavity, a potentially lethal condition. Most patients with cystadenomas do not experience symptoms; thus, cysts are often discovered at routine check-ups. However, sometimes symptoms do appear: the most general being abdominal cramps and discomfort. Severe pain may accompany ovarian torsion, caused by the cysts.
Distinguishing serous and mucinous cystic lesions of the pancreas is of critical importance because mucinous cystic neoplasm has an almost 20% risk of turning malignant . Serous cystadenoma of the pancreas is made up of many small cysts and usually has a grapelike or honeycomb appearance, but a small proportion of cases have oligocystic or macrocystic presentations , which are difficult to distinguish from mucinous cystic neoplasm. A central scar, calcification, and lack of connection with the pancreatic duct are also generally characteristic of serous cystadenoma. Mucinous cystic neoplasm has a round shape and is surrounded by ovary-like stroma. Carcinoembryonic antigen levels, which are increased inside mucinous type cystadenomas, can be determined to help distinguish mucinous cysts from macrocystic serous cystadenomas . Distinction from pancreatic pseudocysts can be made clinically, based on the occurrence of pancreatitis. Adenocarcinoma is distinguished from cysts by its solid appearance. Ultrasonography and computed tomography (CT) are used to describe and characterize the cysts; however, endoscopic ultrasound and fine needle aspiration may be needed to verify the diagnosis .
Biliary cystadenomas are not easy to distinguish clinically from simple cysts or cystadenocarcinomas, therefore imaging and laboratory results are crucial. Both ultrasound and CT can distinguish cystadenomas from simple cysts. However, imaging may not be able to differentiate between cystadenomas and cystadenocarcinomas: both appear as an anechoic mass with echogenic internal septations. Ultrasound images do not show convincing differences between cystadenomas and cystadenocarcinomas regarding their sizes, shapes, or locations . Laboratory tests show normal liver function values, although in some cases the levels of enzymes and bilirubin may be higher. Analysis of cyst fluid can show elevated tumor marker CA19-9 and tumor-associated glycoprotein 72 levels; the latter may differentiate between simple cysts and cystadenomas .
Ultrasonography is the initial examination that a patient suspected of having an ovarian cyst should undergo . Both endovaginal and transabdominal ultrasound can be employed; sonography should yield a good morphological description. Examination by CT and magnetic resonance imaging may provide additional information. Simple ovarian cysts are rarely malignant; many patients diagnosed with ovarian cysts can be managed conservatively. In postmenopausal women with small ovarian cysts, the risk of cancer is extremely small . Combined results of ultrasonography and measurements of carcinoma antigen 125 are useful for following up patients with small cysts.