You are in: eMedicine Specialties > Radiology > GASTROINTESTINAL Pancreas, Serous CystadenomaArticle Last Updated: Jul 17, 2007AUTHOR AND EDITOR INFORMATIONSection 1 of 12
  Author: Barry Lumkin, MD, Consulting Staff, Department of Radiology, Sharp Rees-Stealy Medical Group Barry Lumkin is a member of the following medical societies: American College of Radiology Editors: Glenn Krinsky, MD, Chief of Abdominal Imaging Section, Associate Professor, Department of Radiology, New York University School of Medicine; Bernard D Coombs, MB, ChB, PhD, Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand; Arnold C Friedman, MD, FACR, Professor, Department of Radiology, University of Florida Professor of Radiology, Department of Radiology, Shands-Jacksonville Hospital; Robert M Krasny, MD, Consulting Staff, Department of Radiology, The Angeles Clinic and Research Institute; John Karani, MBBS, FRCR, Consulting Staff, Department of Radiology, King's College Hospital, London Author and Editor Disclosure Synonyms and related keywords: microcystic cystadenoma, glycogen-rich cystadenoma, benign cystic neoplasm of the pancreas INTRODUCTIONSection 2 of 12
  BackgroundCystic lesions of the pancreas are common, and 80-90% of these lesions are pseudocysts or retention cysts. Cystic neoplasms of the pancreas are less common, accounting for about 10-15% of all cystic pancreatic lesions. True cysts of the pancreas are rare. Pancreatic serous cystadenoma used to be referred to as microcystic cystadenoma or glycogen-rich cystadenoma. These terms are no longer considered appropriate. The preferred name is now serous cystadenoma. The two most common cystic neoplasms of the pancreas are serous cystadenoma and mucinous cystic neoplasms (formerly called macrocystic neoplasm, a term that is no longer appropriate). Serous cystadenoma is more common than mucinous cystic neoplasm, with a ratio of about 2:1. Intraductal papillary mucinous tumor (IPMT) is a more recently discovered cystic neoplasm that may be a variant of the mucinous cystic neoplasm. The important point to remember is that serous cystadenoma is benign, whereas the biologic behavior of mucinous cystic neoplasm and IPMT ranges from benign to malignant. Therefore, distinguishing these entities is of the utmost importance. PathophysiologyThese tumors are fairly large at presentation, ranging from 4-20 cm, with an average size of 5-8 cm. Biliary obstruction is rare, and symptoms are generally nonspecific; they include nausea and abdominal pain. If the tumor is large enough, symptoms related to mass effects may predominate. Smaller tumors may be discovered incidentally on abdominal ultrasonography (US) or computed tomography (CT). FrequencyUnited StatesPancreatic serous cystadenoma is classically rare. Over a 55-year period in a large population examined at the Mayo Clinic, only 40 patients underwent surgical treatment for this disease. However, as cross-sectional imaging has improved and become more widely used in aging populations, this tumor is now encountered as an incidental finding with greater frequency. The incidence of this tumor is increased in patients with von Hippel-Lindau disease. Mortality/MorbiditySerous cystadenoma is a benign tumor. Most patients present with nonspecific symptoms such as abdominal pain, nausea, vomiting, or a palpable abdominal mass. SexSerous cystadenoma is more common in women than in men. Most reported male-to-female prevalence ratios range from 1:2 to 1:3. Some reports state that as many as 66% of cases occur in women. AgeThe mean patient age at presentation is 62 years (range, 35-84 y). AnatomyThese tumors occur most commonly in the pancreatic head and body and rarely involve the main pancreatic duct. They are lined by a uniform layer of glycogen-secreting cuboidal cells. Clinical DetailsSigns and symptoms Presenting symptoms are nonspecific. Most commonly, abdominal or back pain, nausea, or vomiting is present. Serous cystadenoma is benign. About one quarter to one third of the patients have no symptoms, and most of the remaining patients present with a variety of nonspecific symptoms such as nausea, anorexia, weight loss, and abdominal pain. Symptoms related to biliary obstruction, other local mass effects, or pancreatitis are rare. The incidence of this tumor is increased in patients with von Hippel-Lindau disease. Diagnosis The main differential diagnoses include the following: mucinous cystic neoplasm, IPMT, pseudocyst, focal pancreatitis, and adenocarcinoma. The diagnosis of pancreatitis and pseudocyst is generally straightforward, especially in a clinical setting of chronic alcoholism with a history of pancreatitis. Imaging findings are usually confirmatory in difficult cases. Adenocarcinoma is most commonly solid and, therefore, infrequently confused with cystic neoplasms. The other entities can have imaging features that are highly suggestive of one entity rather than another. Communication with the pancreatic duct strongly suggests mucinous cystic neoplasm or IPMT instead of serous cystadenoma. A central stellate scar with calcification and a grapelike cluster of cysts and external lobulation strongly suggests serous cystadenoma. However, the imaging features of these entities can overlap considerably; therefore, an analysis of the percutaneous cells and cystic fluid is often required for diagnosis. In fact, approximately 10% of all serous cystadenomas have cystic components larger than 2 cm and cannot be distinguished from mucinous cystic neoplasms. The following table presents the relative values for amylase, carcinoembryonic antigen (CEA), mucin, and viscosity, as well as the cytologic features that can be used to differentiate these entities. Features in the Differentiation of Pancreatic Cysts
Preferred ExaminationFindings from plain radiography and upper GI series are nondiagnostic, except the finding of a classic sunburst central calcification, which is suggestive. Ultrasonography can be used to detect, and sometimes to characterize, the features of this tumor, especially when the classic features are present. In comparison, CT is superior in lesion depiction and characterization, and it is the preferred imaging modality in the initial workup of pancreatic lesions. However, the first test performed is usually ultrasonography, because the typical presenting symptom is abdominal pain and/or nausea. MRI can be a useful problem-solving adjunct in select cases. For example, when an evaluation of the ducts is needed, magnetic resonance cholangiopancreatography (MRCP) can be useful. Limitations of TechniquesWhen stellate calcification or the classic CT features of central sunburst are present in a multilocular cystic mass in an older woman, some institutions accept this as a clearly benign finding. In one series, however, CT was useful in depicting the lesions, but it was not useful in differentiating benign and malignant tumors, serous and mucinous tumors, or pseudocysts and neoplasms. DIFFERENTIALSSection 3 of 12
Pancreas, Adenocarcinoma Pancreas, Mucinous Cystic Neoplasm Pancreatitis, Acute Pancreatitis, Chronic Pseudocyst, Pancreatic Other Problems to Be ConsideredMucinous cystic neoplasm RADIOGRAPHSection 4 of 12
FindingsNo radiographic abnormalities are associated with serous cystadenoma except those related to a mass that is large enough to displace or obstruct the bowel or those related to a prominent central calcification. False Positives/NegativesThe main mimics of this tumor are pseudocysts and mucinous cystic tumors. CT SCANSection 5 of 12
FindingsClassically, these lesions have a mean diameter of 5-8 cm (range, 4-20 cm) and a lobulated external contour. They are composed of a grapelike cluster or honeycomb pattern of 6 or more uniformly sized cysts that are 2 cm or smaller. They tend to occur in the head or neck of the gland, although biliary obstruction is present in only about 15% of the cases. In about 30% of the cases, a central, stellate, late-enhancing scar is present with calcification. Small septa and internal debris may be seen in individual cysts. Because the capsule of these tumors is poorly developed, there is often poor distinction of the tumor from the surrounding pancreatic parenchyma. No communication occurs with the pancreatic duct, except in rare cases (see Images 1-2). The tumor generally has attenuation similar to that of water on nonenhanced scans, and it typically enhances with contrast in a Swiss cheese–like pattern. Some tumors have a few cysts larger than 2 cm. MRISection 6 of 12
FindingsSerous cystadenomas are usually hyperintense on T2-weighted images and hypointense on T1-weighted images (see Image 3). Occasionally, debris (especially hemorrhage) in the cysts alters this signal intensity pattern. The septa are well depicted on T2-weighted images, but the central scar is not. The use of a gradient-echo pulse sequence with a long echo time (TE) may bring out the susceptibility effects from the calcified scar. MRCP is helpful in demonstrating the relationship of the mass to the main pancreatic duct. The main duct is almost never obstructed, but the duct and its branches may be gently splayed and draped. Gadolinium-based contrast agents (gadopentetate dimeglumine [Magnevist], gadobenate dimeglumine [MultiHance], gadodiamide [Omniscan], gadoversetamide [OptiMARK], gadoteridol [ProHance]) have recently been linked to the development of nephrogenic systemic fibrosis (NSF) or nephrogenic fibrosing dermopathy (NFD). For more information, see the eMedicine topic Nephrogenic Fibrosing Dermopathy. The disease has occurred in patients with moderate to end-stage renal disease after being given a gadolinium-based contrast agent to enhance MRI or MRA scans. As of late December 2006, the FDA had received reports of 90 such cases. Worldwide, over 200 cases have been reported, according to the FDA. NSF/NFD is a debilitating and sometimes fatal disease. Characteristics include red or dark patches on the skin; burning, itching, swelling, hardening, and tightening of the skin; yellow spots on the whites of the eyes; joint stiffness with trouble moving or straightening the arms, hands, legs, or feet; pain deep in the hip bones or ribs; and muscle weakness. For more information, see the FDA Public Health Advisory or Medscape. False Positives/NegativesRarely, a fluid-filled diverticulum of the transverse duodenum may mimic a cystic pancreatic mass. ULTRASOUNDSection 7 of 12
FindingsThe cluster-of-grapes pattern and external lobulation may be seen. However, when the cysts are small, the mass can be echogenic (because of the large number of acoustic interfaces), and they can appear solid (see Image 4). This finding can suggest the presence of an adenocarcinoma. The presence of increased through transmission, even if the mass is fairly echogenic, should suggest the diagnosis. NUCLEAR MEDICINESection 8 of 12
FindingsOctreotide (OctreaScan) can be used to detect pancreatic tumors that express somatostatin receptors (eg, neuroendocrine tumors), because the agent is avid for these receptors. However, serous cystadenoma does not typically express these receptors. The ability of positron emission tomographic (PET) imaging to depict these tumors will likely be proven, because it is sensitive to hypermetabolic processes. However, PET is not yet approved for use in the workup of pancreatic lesions. Thallium 201–chloride single photon emission computed tomography (SPECT) can depict malignant, as well as some benign, pancreatic processes. ANGIOGRAPHYSection 9 of 12
FindingsSerous cystadenomas typically demonstrate intense peripheral hypervascularity at angiography, although this finding is nonspecific. INTERVENTIONSection 10 of 12
Medical/Legal Pitfalls
MULTIMEDIASection 11 of 12
REFERENCESSection 12 of 12
Pancreas, Serous Cystadenoma excerpt Article Last Updated: Jul 17, 2007 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
