The IncidentalPancreatic Cyst

Alec J. Megibow, MD, MPHa,*, Mark E. Baker, MDb,Richard M. Gore, MDc, Andrew Taylor, MDd

KEYWORDS

� Pancreatic cyst � Incidental finding � MRI� MDCT � Management

The discovery of a pancreatic cyst in an asymp-tomatic patient presents an immediate challengeto the interpreting radiologist, the clinician whomanages the patient, and patients themselves.The widespread use of multidetector row CT(MDCT) or MRI in an aging population has acceler-ated the discovery of these lesions.

The frequency of pancreatic cysts identified withCT scanning is reported to be between 290 of24039 (1.2%)1 and 73 of 2832 (2.6%).2 For MRI,the reported frequency is significantly higher, atbetween 283 of 1444 (19.9%)3 and 83 of 616(13.5%).4 Therefore, the practicing radiologistcould anticipate seeing a pancreatic cyst anywherefrom 1 to 2 or 14 to 20 times per 100 cases imaged.For some practices, this could be a dailyoccurrence.

Although for many years the most commonpancreatic cyst was believed to be a pseudocyst,cystic pancreatic neoplasms, serous cystade-noma, mucinous cystic tumor (MCT), and intraduc-tal papillarymucinous tumors (IPMTs) nowaccountformost of the pancreatic cysts seen in asymptom-atic individuals.5Cysticpancreatic tumorsaremostoften benign or low-grade indolent neoplasms;however, if the cyst is mucinous (eg, intraductalpapillary mucinous neoplasm or MCT), a variablebut well-established malignant potential exists.6,7

This variable malignant potential of these cysts isthe source of discomfort for all clinicians. The rela-tive inaccessibility of the pancreas (as opposed tocolon, breast, or even lung) to easy biopsy furtherexacerbates the problem.

a Department of Radiology, New York University Langonb Department of Radiology, Cleveland Clinic Foundationc Department of Radiology, NorthShore University Healtof Chicago, 2650 Ridge Avenue, Evanston, IL, USAd Department of Radiology, Virginia Commonwealth Un* Corresponding author.E-mail address: alec.megibow@nyumc.org

Radiol Clin N Am 49 (2011) 349–359doi:10.1016/j.rcl.2010.10.0080033-8389/11/$ – see front matter � 2011 Elsevier Inc. All

When a cyst is discovered on an imaging study ina patientwithout symptomsdirectly referable to thepancreas, the following questions are immediatelyraised: can the lesion be accurately diagnosed oris the appropriate management clear from theexamination, is the best management approachto suggestwatchful waitingwith follow-up imaging,what is the best method for imaging follow-up, andwhat is the optimal frequency of follow-up?

CAN THE LESION EITHER BE ACCURATELYDIAGNOSED OR IS THE APPROPRIATEMANAGEMENT CLEAR FROM THEEXAMINATION?

Morphologic features that can be assessedthrough imaging, allowing cyst characterization,include presence or absence of septa/loculations,presence and location of calcification, location ofthe mass within the pancreas, and presence ofmain pancreatic duct involvement8–11 (Fig. 1).Dense septa are predictive of a serous cystadeno-ma, although oligocystic (few or no septa) variantscan be encountered.12,13 A simple but useful clas-sification system differentiates pancreatic cystsinto four gross morphologic types based solelyon imaging appearance at MDCT: (1) unilocular(pseudocysts, lymphoepithelial cysts, smallIPMTs), (2) microcystic (serous cystadenoma), (3)macrocystic (mucinous cystic tumor, IPMTs), and(4) cysts with a solid component (solid pseudopa-pillary neoplasm, mucinous cystic neoplasm).14

Overlap is anticipated in this classification, but

e Medical Center, New York, NY, USA, Cleveland, OH, USAh System, Pritzker School of Medicine, University

iversity Medical Center, Richmond, VA, USA

rights reserved. radiologic.th

eclinics.com

Fig. 1. Incidental cysts with specific imaging appearances. (A) The cyst in the pancreatic head has diagnosticfeatures of a serous cystadenoma, including dense central septa, central calcification, and slightly larger periph-eral cysts. (B) T2-weightedMRI shows a cyst in the pancreatic tail of a 50–year-old woman. The wall has slight lobu-lation, and a thin septum is present. These findings are typical of a mucinous cystic tumor (MCT). (C) A cyst wasdetected on the axial images; however, the volumetric MDCT data allow three-dimensional analysis, whichenables detection of a neck connecting the cyst to the main pancreatic duct diagnostic of branch duct IPMT.

Megibow et al350

a likely diagnosis can be offered for most masseslarger than 2 cm. Small cysts (<2 cm) will almostalways appear unilocular regardless of origin.15

Serous cystadenoma is a benign lesion. Mostcan be described as either “honeycomb,”“sponge-like,” or oligocystic8 depending on thedensity of septa. Because up to 5% of them canbe either unilocular or contain few septa, the termmicrocystic is no longer used. Calcifications arepresent in approximately 30% of cases and arecentrally located. Lobulation is frequent. Unusualappearances can be encountered, includingobstructive dilatation of the main pancreatic duct,intratumoral hemorrhage, and a solid variant.12,16

Mucinous tumors are classified into two broadcategories: parenchymal and intraductal. Thelatter is subdivided into tumors arising in themain duct, a side branch, or a combined (mixed)form. Parenchymal mucinous lesions, referred toas MCTs, can be suspected based when a cystis present in the tail of the pancreas. They oftenwill have at least one recognizable septum orare unilocular. They are most frequently encoun-tered in perimenopausal women.6 IPMTs or intra-ductal papillary mucinous neoplasms appear as

a dilated main pancreatic duct of variable length.Branch duct IPMT will have a visible communica-tion with the MPD. Visualization of duct com-munication can be defined by three-dimensionalimaging either with MRI/magnetic resonancecholangiopancreatography (MRCP) or MDCT.17

They are seen more often in men.Despite familiarity with the characteristic

imaging features, many pancreatic cysts, particu-larly those smaller 2 cm in maximal diameter, aredifficult if not impossible to specifically charac-terize (Fig. 2). Published studies comparing radio-logic and surgical diagnosis of pancreatic cystsconsistently reinforce the limitations of preopera-tive imaging diagnosis,15,18 creating uncertaintyfor radiologists confronted with one of theselesions, because some will be benign and otherswill be low-grade neoplasms.

IS THE BEST MANAGEMENT APPROACHTO SUGGEST WATCHFUL WAITINGWITH FOLLOW-UP IMAGING?

Most incidental pancreatic cysts are either benignor low-grade neoplasms. Among 61 asymptomatic

Fig. 2. Lack of specificity in the radiologic diagnosis of pancreatic cysts. (A) T2-weighted MR shows a septated cystin pancreatic body. The appearance is compatible with MCT. (B) Gadolinium-enhanced image shows the cyst tohave a thick wall, thick septum, and mural nodules. This appearance makes surgical removal advisable. The lesionwas a neuroendocrine tumor.

Fig. 3. Mural nodules. Ill-defined soft tissue density isseen along the superior aspect of this cyst (arrow-head). Mural nodules and irregularity may be difficultto appreciate on MDCT but may be more evident onMRI or endoscopic ultrasound. Because of thesefeatures combined with its size (4 cm in length), thislesion was considered surgical. Pathology showedonly dysplasia, no carcinoma.

The Incidental Pancreatic Cyst 351

patients in a cohort of 212 who had pancreaticcysts in whom operative correlation existed, 28%of asymptomatic cysts were mucinous cysticneoplasms, 27% were intraductal papillarymucinous neoplasms, 17% were serous cystade-nomas, 3.8% were pseudocysts, and 2.5% wereductal adenocarcinomas.19 Given that only 20.8%of the asymptomatic cysts in this series werecompletely benign, the fact that nonoperativemanagement is controversial is understandable.20

Nonetheless, ample literature supports surveil-lance of asymptomatic pancreatic cysts21–28 asopposed to immediate surgical resection, becausethey grow extremely slowly, if at all, even if they areneoplastic.

The imaging-based decision whether to resector observe a pancreatic cyst depends predomi-nantly on cyst size. Most studies concur that thefrequency of malignancy in a cyst smaller than3 cm is extremely low, although some recommend2.5 cm as a maximal diameter for nonsurgicalmanagement.29 However, a significant percentageof these lesions smaller than 3 cmwill bemucinous,but rarely is invasive cancer found in these lesionsonresection.25 Studies of patients in whom cysts havebeen resected or aspirated have found that malig-nancy or premalignancy does not correlate withcyst size alone; these studies consider mucinouslesions of any size to be premalignant.18,20,30,31

A retrospective case series reviewed 79 patientswho underwent long-term follow-up, either for 5years with imaging (n 5 22) or 8 years with clinicalfollow-up (n5 27), who were diagnosed with small(�2 cm) simple pancreatic cysts on sonography orCT from 1985 to 1996. Of the 22 patients whounderwent radiologic follow-up, 13 (59%) hadcysts that remained unchanged or became smaller

(mean size, 8 mm; mean follow-up, 9 years) and 9(41%) had cysts that enlarged, from a mean of 14mm to a mean of 26 mm (mean follow-up, 8 years).Of the 27 patients who underwent clinical or ques-tionnaire follow-up (mean follow-up, 10 years),none developed symptomatic pancreatic disease.Eighteen patients (23%) died within 8 yearswithout adequate radiologic follow-up, althoughnone of pancreas-related causes.32 This experi-ence would support the surveillance of cystssmaller 3 cm regardless of origin.

Size alone cannot be an independent decision-making variable. Radiologists must attempt toexclude the presence of morphologic abnormali-ties that raise the specter of a complex cyst. Aside

Megibow et al352

from a cyst larger than 3 cm, features that areworrisome include the presence of mural nodules,dilatation of the common bile duct, dilatation ofthe main pancreatic duct larger than 6 mm, ductwall enhancement, and lymphadenopathy27,33–37

(Fig. 3).When a cyst larger than 1 cm is detected, before

a specific radiologic-based decision is made,a dedicated “pancreas-style” study should be per-formed. Because smaller cysts (closer to 1 cm) aremore likely to be benign, the timing of this exami-nation is better determined through clinical deci-sion rather than according to a rigid algorithm.One could make a case for delaying the character-ization study for several months6–12 for lesionscloser to 1 cm than to 3 cm. If MDCT is used forlesion characterization, a dual-phase acquisitionin both pancreatic and portal venous phases using

Fig. 4. Follow-up of side branch IPMT. (A) MDCT study detemergency department in 2003 for lower abdominal paweeks later study provided a data set that allowed creatioof IPMT. Because the lesion was smaller than 2 cm, the pawas advised to have the lesion followed up with MRI to decobtained in 2010; the lesion has not changed in the past

narrow detector configuration and intravenouscontrast is the appropriate protocol. Thin-sectionimages should be available on a workstation tofacilitate three-dimensional analysis (Fig. 4). Alter-natively, MRI performed at 1.5T can be used. Thestudy should include sequences that displayin and out of phase T1 and T2 (preferably withfat suppression), and fat suppressed three-dimensional gadolinium-enhanced sequences inpancreatic, portal, and equilibrium phases. Addi-tionally, respiratory triggered three-dimensionalMRCP is necessary.38 Secretin administrationmay facilitate visualization of the cyst’s communi-cation with the main pancreatic duct.39

Many cysts are smaller than 10mm. In a study of421 cysts, 144 (34%) were in this size range.40

Cysts of this size are frequently detected at MRI;they are not easily characterized through imaging.

ected this lesion in a middle-aged woman seen in thein. (B) A “pancreatic-style” MDCT performed severaln of the CT pancreatogram confirming the diagnosistient elected follow-up for the lesion. (C) The patientrease radiation exposure. This T2-weighted image was7 years.

The Incidental Pancreatic Cyst 353

Recommendations for following up these cystscannot be made based on the appearance atimaging alone.

Non–imaging-based parameters are critical inthe final recommendation to follow-up, resection,or ignore. The presence or absence of patientsymptoms (eg, weight loss, jaundice, diabetes,anorexia) is a critical component of these de-cisions.41 Leeandcolleagues42 found that in asymp-tomatic patients with pancreatic cysts smaller than3 cm, the incidence of occult malignancy was3.3%, whereas 90% of patients with malignantlesions were symptomatic.

The treatment philosophy of a given institutionmust also be factored into the decision-makingprocess. A meta-analysis compared1 initial pan-creaticoduodenectomy,2 yearly noninvasive radio-graphic surveillance,3 yearly invasive surveillancewith endoscopic ultrasound, and4 the do-nothing

Fig. 5. Follow-up images of oligocystic serous cystadenomayears old in 2005. The lesion has been stable for the entireunderwent an endoscopic ultrasound–assisted aspiratiopatient was dismissed from further follow-up this year; hoatic type symptoms, she would require reevaluation with

approach for all cysts larger than 2 cm in thepancreatic head. Survival was maximized if allcysts were resected; however, when measuringquality-adjusted survival, the do-nothing approachmaximized quality of life in patients younger than75 years of age who had cysts smaller than3 cm. Once age exceeded 85 years, noninvasivesurveillance dominated. Initial pancreaticoduode-nectomy did not maximize quality of life in anyage group or cyst size.43

If the decision is made to resect a cyst smallerthan 3 cm, every attempt should be made to deter-mine a specific diagnosis. Endoscopic ultrasoundwith fine-needle aspiration is the most widely usedtechnique to obtain cyst content for analysis.Cyst size is the primary determinate of successfulaspiration.44 A carcinoembryonic antigen levelin the aspirate of 192 ng/mL has a high specificityfor discriminating mucinous from nonmucinous

in (A) 2005, (B) 2008, and (C) 2010. The patient was 56period of observation. Because of the size, the patientn, which confirmed glycogen-rich serous fluid. Thewever, she was told that if she developed any pancre-further imaging.

Fig. 6. (A) Irregular pancreatic body cyst is seen in this middle-aged man in 2006. No pancreas-related symptomswere present. The mass was somewhat irregular. Aspiration under endoscopic ultrasound was suggested;however, this procedure did not yield a diagnostic sample. Follow-up was advised. (B) Follow-up MRI in 2010.T2-weighted image clearly shows the mass to be a branch duct IPMT. The lesion has not increased in size in4 years. Further follow-up is unnecessary if the patient remains asymptomatic.

Fig. 7. Growth of lesion. (A) T2-weighted MRI from patient with vague abdominal symptoms seen in 2007 showsa high signal mass in the pancreatic head. It has no internal septa or debris, and the remainder of the pancreaswas normal. Follow-up was recommended. (B) T2-weighted MRI in same patient from 2008. The mass has grown.An aspiration under endoscopic ultrasound guidance was attempted but was nondiagnostic. The patient electedto continue follow-up. (C) T2-weighted MRI in the same patient in 2009. Growth has continued. The lesionremains otherwise unchanged with no interval development of worrisome features. Surgery was recommended,and no new attempt at aspiration was made. The mass was a pseudocyst.

Megibow et al354

The Incidental Pancreatic Cyst 355

cysts, with an accuracy surpassing cyst mor-phology.45,46 Amylase levels of less than 250exclude pseudocyst. However, a high degree ofoverlap exists between the values obtained ataspiration.47 There is variability among institutionsin the ability to accurately analyze the often smallvolumes of pancreatic aspirate. The overall sensi-tivity of endoscopic ultrasound aspiration cytologyis low; however, the specificity is adequate indifferentiating mucinous from nonmucinous cysticlesions.48

Box 1Recommendations for radiologists confrontedwith an incidental pancreatic cyst

1. Surgery should be considered for patientswith cysts larger than 3 cm.

2. If the lesion is a serous cystadenoma, surgeryis deferred until the cyst is larger than 4 cm.

3. Patients with simple cysts smaller than 3 cmcan be followed up, but attempts should bemade to characterize cysts larger than 2 cmat detection; if this cannot be done basedon the available imaging study, MRI is thepreferred procedure.

4. Cysts smaller than 1 cm cannot be furthercharacterized by imaging, but can be fol-lowed up less frequently than cysts largerthan 3 cm; in elderly patients (>80 years ofage), these cysts likely will not requirefurther investigation.

5. Aspiration is strongly advised to excludepseudocyst before any surgery is performed.

6. Patients must remain asymptomatic duringthe follow-up period.

From Berland LL, Silverman SG, Gore RM, et al.Managing incidental findings on abdominal CT: whitepaper of the ACR incidental findings committee. J AmColl Radiol 2010;7(10):754–73.

WHAT IS THE BEST FOLLOW-UP METHOD?

Assuming that a lesion meets strictly appliedcriteria for follow-up (<3 cm, no mural nodules,no main pancreatic duct dilatation, asymptom-atic), follow-up studies are often recommendedin the radiologic report. Two questions are raised:what is the frequency of follow-up, and what is theoptimal method of follow-up?

The frequency of follow-up examinations is notresolved. A conservative management would beto follow up a cyst for 24 months at 6-month inter-vals and then yearly for a second 24 months,declaring stability after 4 years.49 The Sendaiguidelines recommend all cysts smaller than1 cm be followed each year, all cysts from 1 to2 cm followed as described earlier, cysts from 2to 3 cm be followed every 3 to 6 months, and allcysts larger than 3 cm be resected.23 Based onlongitudinal observation of 166 cysts in 150patients, a second approach suggests having thefirst follow-up occur 2 years after baseline.40

American College of Radiology (ACR) guidelinesrecommend a single follow-up in 1 year for lesionssmaller than 2 cm; a follow-up of every 6 monthsfor 2 years and then yearly for lesions 2 to 3 cm;and for lesions larger than 3 cm, resect unlessthey are serous cystadenoma or proven to bepseudocyst through aspiration. All of these guide-lines suggest that patients must remain asymp-tomatic during the follow-up period (Fig. 5).

The choice of follow-up method is important.The ACR subcommittee on incidental pancreaticlesions recommends MRI as the preferred follow-up procedure based on superior contrast resolu-tion making the detection of septa, nodules, andmain pancreatic duct communication easiest torecognize17 and the lack of ionizing radiation50

(Fig. 6). Cost and resource availability must befactored into this decision. For patients olderthan 60 years, radiation issues may not be ascompelling. Regardless of the choice of follow-up procedure, care must be taken to assure thatmeasurements are made carefully and con-sistently.51 The lesion must be carefully measured;

not only must the slice number and series appearin the report but also electronic calipers must beplaced on the exact image used to determine thediameters. Currently, no consensus has definedgrowth. The precision of manual measurement iswell-known to be inversely related to the lesiondiameter. Thus, determining whether the reportedgrowth of a small lesion is true growth or measure-ment error may be difficult. Considerable researchis currently evaluating semiautomated lesion seg-mentation, which will overcome this problem.52

Growth alone may not be sufficient to recommendsurgery; the authors believe that cyst contentshould be aspirated before surgical excision isperformed (Fig. 7).

Recent reports have documented ductal adeno-carcinoma developing in a remote site within thepancreas from a known branch duct IPMT.53,54

This finding is not surprising in that many believethe presence of a mucinous lesion is a signal ofincreased risk of pancreatic neoplasm anywherewithin the gland. In most of these cases, the targetcyst remains unchanged. The development ofthese lesions is thought to reflect a field effectwithin the pancreas, with the cyst being a signalof a gland that is at risk for developing carcinoma.Increased numbers of pancreatic intraepithelialneoplasia lesions, believed to be precursor lesionsfor development of ductal adenocarcinoma, are

Fig. 8. Flow chart for imaging workup of incidental pancreatic masses in asymptomatic patients. As with all guidelin s, these are not meant to be a rigid set of rules, butrather a starting point for clinically relevant decision making. BD-IPMN, branch duct intraductal papillary mucino s neoplasm; US, ultrasound. a Signs and symptomsinclude hyperamylasemia, recent onset diabetes, severe epigastric pain, weight loss, steatorrhea, or jaundice. Consider decreasing interval if younger, omittingwith limited life expectancy. Recommend limited T2-weighted MRI for routine follow-ups. c Recommend pancreas-d icated MRI with MRCP. d If no growth after 2 years,follow yearly. If growth or suspicious features develop, consider resection. (From Berland LL, Silverman SG, Gore RM, et al. Managing incidental findings on abdominalCT: white paper of the ACR incidental findings committee. J Am Coll Radiol 2010;7(10):754–73.)

Megibow

etal

356

eub

ed

The Incidental Pancreatic Cyst 357

seen in resected specimens.55 Should a significantfrequency of cancer develop elsewhere in thepancreas of patients with any type of cyst,follow-up imaging recommendations and surgicalmanagement of the cysts will be altered.

RECOMMENDATIONS FOR RADIOLOGISTS

The pancreas subcommittee of the ACRcommittee on incidental lesions developed thefollowing recommendations for radiologists con-fronted with an incidental pancreatic cyst (a cystseen in an asymptomatic patient (Box 1).

These are recommendations, not guidelines norcare standards. Fig. 8 provides these recommen-dations in flow-chart format. Individual patientcharacteristics must be factored into every deci-sion. Many clinicians who read this probablyknow of single case examples that are contraryto the above recommendations. However, theextensive observational experience of the authorsand concordant experience documented in thepublished literature validate the approach outlinedin this article as a reasonable departure point foranalyzing patients with incidental pancreaticcysts.

REFERENCES

1. Spinelli KS, Fromwiller TE, Daniel RA, et al. Cystic

pancreatic neoplasms: observe or operate. Ann

Surg 2004;239(5):651–7 [discussion: 657–9].

2. Laffan TA, Horton KM, Klein AP, et al. Prevalence of

unsuspected pancreatic cysts on MDCT. AJR Am J

Roentgenol 2008;191(3):802–7.

3. Zhang XM, Mitchell DG, Dohke M, et al. Pancreatic

cysts: depiction on single-shot fast spin-echo MR

images. Radiology 2002;223(2):547–53.

4. Lee KS, Sekhar A, Rofsky NM, et al. Prevalence of

incidental pancreatic cysts in the adult population

on MR imaging. Am J Gastroenterol 2010;2010:30.

5. Simeone DM. SSAT/AGA/ASGE state of the art

conference on cystic neoplasms of the pancreas.

J Gastrointest Surg 2008;12(8):1475–7.

6. Adsay NV. Cystic neoplasia of the pancreas:

pathology and biology. J Gastrointest Surg 2008;

12(3):401–4.

7. Parra-Herran CE, Garcia MT, Herrera L, et al. Cystic

lesions of the pancreas: clinical and pathologic

review of cases in a five year period. JOP 2010;

11(4):358–64.

8. Procacci C, Graziani R, Bicego E, et al. Serous

cystadenoma of the pancreas: report of 30 cases

with emphasis on the imaging findings. J Comput

Assist Tomogr 1997;21(3):373–82.

9. Procacci C, Biasiutti C, CarbogninG, et al. Character-

ization of cystic tumors of the pancreas: CTaccuracy.

J Comput Assist Tomogr 1999;23(6):906–12.

10. Rautou PE, Levy P, Vullierme MP, et al. Morphologic

changes in branch duct intraductal papillary

mucinous neoplasms of the pancreas: a midterm

follow-up study. Clin Gastroenterol Hepatol 2008;

6(7):807–14.

11. Procacci C, Carbognin G, Accordini S, et al. CT

features of malignant mucinous cystic tumors of

the pancreas. Eur Radiol 2001;11(9):1626–30.

12. Choi JY, Kim MJ, Lee JY, et al. Typical and atypical

manifestations of serous cystadenoma of the

pancreas: imaging findings with pathologic correla-

tion. AJR Am J Roentgenol 2009;193(1):136–42.

13. Cohen-Scali F, Vilgrain V, Brancatelli G, et al.

Discrimination of unilocular macrocystic serous

cystadenoma from pancreatic pseudocyst and

mucinous cystadenoma with CT: initial observations.

Radiology 2003;228(3):727–33.

14. Sahani DV, Kadavigere R, Saokar A, et al. Cystic

pancreatic lesions: a simple imaging-based classifica-

tion system for guiding management. Radiographics

2005;25(6):1471–84.

15. Walsh RM, Henderson JM, Vogt DP, et al. Prospec-

tive preoperative determination of mucinous pancre-

atic cystic neoplasms. Surgery 2002;132(4):628–33

[discussion: 633–4].

16. Takeshita K, Kutomi K, Takada K, et al. Unusual

imaging appearances of pancreatic serous cystade-

noma: correlation with surgery and pathologic anal-

ysis. Abdom Imaging 2005;15:15.

17. Waters JA, Schmidt CM, Pinchot JW, et al. CT vs

MRCP: optimal classification of IPMN type and

extent. J Gastrointest Surg 2008;12(1):101–9.

18. Correa-Gallego C, Ferrone CR, Thayer SP, et al.

Incidental pancreatic cysts: do we really know

what we are watching? Pancreatology 2010;

10(2–3):144–50.

19. Fernandez-del Castillo C, Targarona J, Thayer SP,

et al. Incidental pancreatic cysts: clinicopathologic

characteristics and comparison with symptomatic

patients. Arch Surg 2003;138(4):427–33 [discus-

sion: 433–4].

20. Walsh RM, Vogt DP, Henderson JM, et al. Man-

agement of suspected pancreatic cystic neoplasms

based on cyst size. Surgery 2008;144(4):677–84

[discussion: 684–5].

21. Lahav M, Maor Y, Avidan B, et al. Nonsurgical

management of asymptomatic incidental pancreatic

cysts. Clin Gastroenterol Hepatol 2007;5(7):813–7.

22. Sahani DV, Saokar A, Hahn PF, et al. Pancreatic

cysts 3 cm or smaller: how aggressive should treat-

ment be? Radiology 2006;238(3):912–9.

23. Tanaka M, Chari S, Adsay V, et al. International

consensus guidelines for management of intraductal

papillary mucinous neoplasms and mucinous cystic

Megibow et al358

neoplasms of the pancreas. Pancreatology 2006;

6(1–2):17–32.

24. Walsh RM, Vogt DP, Henderson JM, et al. Natural

history of indeterminate pancreatic cysts. Surgery

2005;138(4):665–70 [discussion: 670–1].

25. Allen PJ, D’Angelica M, Gonen M, et al. A selective

approach to the resection of cystic lesions of the

pancreas: results from 539 consecutive patients.

Ann Surg 2006;244(4):572–82.

26. Edirimanne S, Connor SJ. Incidental pancreatic

cystic lesions. World J Surg 2008;32(9):2028–37.

27. Brounts LR, Lehmann RK, Causey MW, et al.

Natural course and outcome of cystic lesions

in the pancreas. Am J Surg 2009;197(5):619–22

[discussion: 622–3].

28. Bassi C, Sarr MG, Lillemoe KD, et al. Natural history

of intraductal papillary mucinous neoplasms (IPMN):

current evidence and implications for management.

J Gastrointest Surg 2008;12(4):645–50.

29. Gomez D, Rahman SH, Wong LF, et al. Predictors of

malignant potential of cystic lesions of the pancreas.

Eur J Surg Oncol 2008;34(8):876–82.

30. Ceppa EP, De la Fuente SG, Reddy SK, et al.

Defining criteria for selective operative management

of pancreatic cystic lesions: does size really matter?

J Gastrointest Surg 2010;14(2):236–44.

31. Goh BK, Tan YM, Cheow PC, et al. Cystic lesions of

the pancreas: an appraisal of an aggressive resec-

tional policy adopted at a single institution during

15 years. Am J Surg 2006;192(2):148–54.

32. Handrich SJ, HoughDM, Fletcher JG, et al. The natural

history of the incidentally discovered small simple

pancreatic cyst: long-term follow-up and clinical impli-

cations. AJR Am J Roentgenol 2005;184(1):20–3.

33. Lee SH, Shin CM, Park JK, et al. Outcomes of cystic

lesions in the pancreas after extended follow-up. Dig

Dis Sci 2007;52(10):2653–9.

34. Salvia R, Crippa S, Falconi M, et al. Branch-duct in-

traductal papillary mucinous neoplasms of the

pancreas: to operate or not to operate? Gut 2007;

56(8):1086–90.

35. Bassi C, Crippa S, Salvia R. Intraductal papillary

mucinous neoplasms (IPMNs): is it time to (some-

times) spare the knife? Gut 2008;57(3):287–9.

36. Javle M, Shah P, Yu J, et al. Cystic pancreatic

tumors (CPT): predictors of malignant behavior.

J Surg Oncol 2007;95(3):221–8.

37. Manfredi R, Graziani R, Motton M, et al. Main

pancreatic duct intraductal papillary mucinous

neoplasms: accuracy of MR imaging in differentia-

tion between benign and malignant tumors

compared with histopathologic analysis. Radiology

2009;253(1):106–15.

38. Sodickson A, Mortele KJ, Barish MA, et al. Three-

dimensional fast-recovery fast spin-echo MRCP:

comparison with two-dimensional single-shot fast

spin-echo techniques. Radiology 2006;238(2):549–59.

39. Carbognin G, Pinali L, Girardi V, et al. Collateral

branches IPMTs: secretin-enhanced MRCP. Abdom

Imaging 2007;32(3):374–80.

40. Das A, Wells CD, Nguyen CC. Incidental cystic

neoplasms of pancreas: what is the optimal interval

of imaging surveillance? Am J Gastroenterol 2008;

103(7):1657–62.

41. Taouli B, Vilgrain V, Vullierme MP, et al. Intraductal

papillary mucinous tumors of the pancreas: helical

CT with histopathologic correlation. Radiology

2000;217(3):757–64.

42. Lee CJ, Scheiman J, Anderson MA, et al. Risk of

malignancy in resected cystic tumors of the

pancreas < or 53 cm in size: is it safe to observe

asymptomatic patients? A multi-institutional report.

J Gastrointest Surg 2008;12(2):234–42.

43. Weinberg BM, Spiegel BM, Tomlinson JS, et al.

Asymptomatic pancreatic cystic neoplasms: maxi-

mizing survival and quality of life using Markov-

based clinical nomograms. Gastroenterology 2010;

138(2):531–40.

44. Walsh RM, Zuccaro G, Dumot JA, et al. Predicting

success of endoscopic aspiration for suspected

pancreatic cystic neoplasms. JOP 2008;9(5):612–7.

45. Brugge WR, Lewandrowski K, Lee-Lewandrowski E,

et al. Diagnosis of pancreatic cystic neoplasms:

a report of the cooperative pancreatic cyst study.

Gastroenterology 2004;126(5):1330–6.

46. Linder JD, Geenen JE, Catalano MF. Cyst fluid anal-

ysis obtained by EUS-guided FNA in the evaluation

of discrete cystic neoplasms of the pancreas:

a prospective single-center experience. Gastrointest

Endosc 2006;64(5):697–702.

47. van der Waaij LA, van Dullemen HM, Porte RJ. Cyst

fluid analysis in the differential diagnosis of pancre-

atic cystic lesions: a pooled analysis. Gastrointest

Endosc 2005;62(3):383–9.

48. Thosani N, Thosani S, Qiao W, et al. Role of EUS-

FNA-based cytology in the diagnosis of mucinous

pancreatic cystic lesions: a systematic review and

meta-analysis. Dig Dis Sci 2010;55(10):2756–66.

49. Salvia R, Crippa S, Partelli S, et al. Pancreatic cystic

tumours: when to resect, when to observe. Eur Rev

Med Pharmacol Sci 2010;14(4):395–406.

50. Macari M, Lee T, Kim S, et al. Is gadolinium neces-

sary for MRI follow-up evaluation of cystic lesions

in the pancreas? Preliminary results. AJR Am J

Roentgenol 2009;192(1):159–64.

51. Maimone S, Agrawal D, Pollack MJ, et al. Variability

in measurements of pancreatic cyst size among

EUS, CT, and magnetic resonance imaging modali-

ties. Gastrointest Endosc 2010;71(6):945–50.

52. Pauls S, Kurschner C, Dharaiya E, et al. Comparison

of manual and automated size measurements of

lung metastases on MDCT images: potential influ-

ence on therapeutic decisions. Eur J Radiol 2008;

66(1):19–26.

The Incidental Pancreatic Cyst 359

53. Tada M, Kawabe T, Arizumi M, et al. Pancreatic

cancer in patients with pancreatic cystic lesions:

a prospective study in 197 patients. Clin Gastroen-

terol Hepatol 2006;4(10):1265–70.

54. Uehara H, Nakaizumi A, Ishikawa O, et al. Develop-

ment of ductal carcinoma of the pancreas during

follow-up of branch duct intraductal papillary

mucinous neoplasm of the pancreas. Gut 2008;

57(11):1561–5.

55. Takaori K, Kobashi Y, Matsusue S, et al. Clinico-

pathological features of pancreatic intraepithelial

neoplasias and their relationship to intraductal

papillary-mucinous tumors. J Hepatobiliary Pancreat

Surg 2003;10(2):125–36.