DOI: 10.1148/radiol.2432060710
(Radiology 2007;243:607-608.)
© RSNA, 2007
Pancreatic Cysts 3 cm or Smaller
Brian K. P. Goh, MBBS, MRCS, MMed
Department of Surgery, Singapore General Hospital, Outram Rd, Singapore 169608
e-mail: bsgkp{at}hotmail.com
Editor:
I would like to raise several concerns regarding the article by Dr Sahani and colleagues (1), published in the March 2006 issue of Radiology, in which the authors concluded that small (
3 cm) pancreatic cysts can be followed up safely by means of imaging because 75 of 86 (87%) of these cysts were benign. First, the authors classified mucinous and neuroendocrine neoplasms as benign lesions. However, as briefly pointed out by the authors, on the basis of present evidence most investigators regard these lesions as, at the very least, potentially malignant (2). Of the 75 "benign" lesions in their study, 36 were mucinous or neuroendocrine neoplasms. Hence, at least 47 of 86 (55%) small pancreatic cysts were potentially malignant or malignant. This percentage is potentially even larger, as 25 of the benign cysts were "unclassified," which were cysts with fluid carcinoembryonic antigen (CEA) levels between 5 µg/L and 200 µg/L, with no cytologic evidence of malignancy. However, on the basis of recent data, approximately 25% of cysts (14 of 60) with fluid CEA levels of <200 µg/L would be mucinous (3). Hence, it can be estimated that approximately 53 of 86 (62%) small (3 cm) cysts in their study were at least potentially malignant. At our institution, we too have found that a substantial proportion (six of 16) of small (2 cm) pancreatic cysts were potentially or frankly malignant (4).
Second, the authors found that only one of 36 small unilocular cysts was borderline and that none were frankly malignant. However, a substantial proportion were potentially malignant, as 18 of 36 small unilocular cysts were mucinous neoplasms and 11 were "benign unclassified" cysts. They also found that these cysts were less likely to be malignant compared with septated cysts. Our experience was similar—of 23 patients with unilocular cysts, none had a frankly malignant lesion, and the cysts were substantially less likely to be malignant compared with other cysts (5). However, three of eight (38%) patients with small (2 cm), incidental unilocular pancreatic cysts had a potentially malignant lesion (5).
Finally, in my opinion the authors' conclusions are highly controversial. They suggest that all small incidental pancreatic cysts can be safely monitored with imaging on the basis of their results, as only 12% were malignant and one of 38 patients managed conservatively had a cyst that demonstrated change in size or morphology. However, I would interpret their results to demonstrate that small incidental cysts should not be managed conservatively with imaging, since approximately 62% of these were potentially malignant or malignant. The good outcome demonstrated is of little value because of the short follow-up duration (21.8 months). Observation studies presently suggest a time lag of up to 10 years for malignant transformation of mucinous lesions (6). Hence, all small pancreatic cysts should be further investigated with endoscopic ultrasonography with cyst fluid analysis and/or resected because of the high risk of potentially malignant lesions. This is especially true in surgically fit patients since it is not prudent to observe potentially malignant or malignant lesions in patients with a long life expectancy.
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References
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- Sahani DV, Saokar A, Hahn PF, Brugge WR, Fernandez-del Castillo C. Pancreatic cysts 3 cm or smaller: how aggressive should treatment be? Radiology 2006;238:912–919.[Abstract/Free Full Text]
- Le Borgne J, de Calan L, Partensky C. Cystadenomas and cystadenocarcinomas of the pancreas: a multiinstitutional retrospective study of 398 cases. French Surgical Association. Ann Surg 1999;230:152–161.[CrossRef][Medline]
- Brugge WR, Lewandrowski K, Lee-Lewandrowski E, et al. Diagnosis of pancreatic cystic neoplasms: a report of the cooperative pancreatic cyst study. Gastroenterology 2004;126:1330–1336.[CrossRef][Medline]
- Goh BK, Tan YM, Cheow PC, et al. Cystic lesions of the pancreas: an appraisal of an aggressive resection policy adopted at a single institution during 15 years. Am J Surg 2006;192:148–154.[CrossRef][Medline]
- Goh BK, Tan YM, Cheow PC, et al. ‘Simple’ pancreatic cysts demonstrated on computed tomography: clinicopathological characteristics and a comparison with ‘complex’ cysts [abstr]. HPB Surg 2006;8(S1):35.
- Sohn TA, Yeo CJ, Cameron JL, et al. Intraductal papillary mucinous neoplasms of the pancreas: an updated experience. Ann Surg 2004;239:788–799.[CrossRef][Medline]
Response
Dushyant V. Sahani, MD,**,
Anuradha Saokar, MD,**, and
Carlos Fernandez-del Castillo, MD
Department of Radiology, Division of Abdominal Imaging,*
and Department of Surgery, Massachusetts General Hospital, White 270, 55 Fruit Street, Boston, MA 02114
e-mail: dsahani{at}partners.org
We appreciate the comments from Dr Goh on our article "Pancreatic Cysts 3 cm or Smaller: How Aggressive Should Treatment Be?" (1). Pancreatic cysts are caused by a spectrum of pathologic conditions that include benign lesions, such as serous cystadenomas and pseudocysts, as well as potentially malignant neoplasms, such as neuroendocrine tumors, mucinous cystic neoplasms (MCNs), and intraductal mucinous neoplasms (IPMNs). The degree of epithelial dysplasia is used to classify the latter two neoplasms into: benign adenomas, borderline neoplasms, carcinoma in situ, and invasive cancers (2). Given the rapid increase in the incidence of small pancreatic cysts at imaging, pancreatic surgery that may be morbid might not be appropriate in all patients. According to previous reports and our own experience, small (<3 cm) IPMNs and MCNs are often benign (3). Despite the potential risk of malignancy in MCNs and IPMNs, the time required for adenoma to carcinoma transformation is thought to be several years. In lieu of the small but potential risk of malignancy, these small cysts should not be ignored but should be followed up with imaging, especially in older and otherwise asymptomatic individuals. On the other hand, small cysts in the younger patients should be managed more aggressively. At present, guidelines for the management of small pancreatic cysts are evolving, and the current thinking is to offer conservative management in quite a few of these patients (4).
We again emphasize that the patient's age and clinical symptoms in combination with imaging features, including presence or absence of septations and mural nodules, are useful for deciding management. Septated cysts and those with a mural nodule and/or solid component should be pursued with a more aggressive approach, while the small unilocular cysts can be managed conservatively. Similar recommendations have been made by Handrich et al (4) where small, simple pancreatic cysts can be safely followed up with imaging.
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References
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- Sahani DV, Saokar A, Hahn PF, Brugge WR, Fernandez-Del Castillo C. Pancreatic cysts 3 cm or smaller: how aggressive should treatment be? Radiology 2006;238:912–919.[Abstract/Free Full Text]
- Von Klöppel G, Solcia E, Longnecker DS, Capella C, Sobin LH. Histological typing of tumors of the exocrine pancreas. In: Collaboration with Pathologists in 7 Countries Series: World Health Organization—international histologic classification of tumors. New York, NY: Springer-Verlag, 1998.
- Tanaka M, Chari S, Adsay V, et al. International consensus guidelines for management of intraductal papillary mucinous neoplasms and mucinous cystic neoplasms of the pancreas. Pancreatology 2006;6:17–32.[CrossRef][Medline]
- Handrich SJ, Hough DM, Fletcher JG, Sarr MG. The natural history of the incidentally discovered small simple pancreatic cyst: long-term follow-up and clinical implications. AJR Am J Roentgenol 2005;184:20–23.[Abstract/Free Full Text]
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