doi:10.1136/gut.2007.129684 2008;57;339-343; originally published online 27 Jul 2007; Gut Mizukami, N Yanagawa, T Fujii, T Obara, T Okumura and Y Kohgo S Tanno, Y Nakano, T Nishikawa, K Nakamura, J Sasajima, M Minoguchi, Y results without mural nodules: long-term follow-up papillary-mucinous neoplasms of the pancreas Natural history of branch duct intraductal http://gut.bmj.com/cgi/content/full/57/3/339 Updated information and services can be found at: These include: References http://gut.bmj.com/cgi/content/full/57/3/339#otherarticles 1 online articles that cite this article can be accessed at: http://gut.bmj.com/cgi/content/full/57/3/339#BIBL This article cites 31 articles, 3 of which can be accessed free at: service Email alerting the top right corner of the article Receive free email alerts when new articles cite this article - sign up in the box at Notes http://journals.bmj.com/cgi/reprintform To order reprints of this article go to: http://journals.bmj.com/subscriptions/ go to: GutTo subscribe to on 11 August 2008 gut.bmj.comDownloaded from Natural history of branch duct intraductal papillary- mucinous neoplasms of the pancreas without mural nodules: long-term follow-up results S Tanno, 1 Y Nakano, 2 T Nishikawa, 2 K Nakamura, 2 J Sasajima, 2 M Minoguchi, 2 Y Mizukami, 2 N Yanagawa, 2 T Fujii, 2 T Obara, 2 T Okumura, 1 Y Kohgo 2 1 Department of General Medicine, Asahikawa Medical College, Asahikawa, Japan; 2 Department of Gastroenterology and Hematology/Oncology, Asahikawa Medical College, Asahikawa, Japan Correspondence to: Dr S Tanno, Department of General Medicine, Asahikawa Medical College, 2-1-1-1 East Midorigaoka, Asahikawa, Hokkaido, 078-8510, Japan; tanno1se@asahikawa-med. ac.jp Revised 10 June 2007 Accepted 17 July 2007 Published Online First 27 July 2007 ABSTRACT Background and aim: Although branch duct intraductal papillary-mucinous neoplasms (IPMNs) of the pancreas without mural nodules are frequently observed in asymptomatic subjects, the natural history of these lesions has never been studied. The aim of this study was to elucidate the natural history of branch duct IPMNs without mural nodules. Methods: Eighty-two patients who had no apparent mural nodules on initial examination were selected for follow-up. All subjects underwent examinations by imaging modalities including endoscopic retrograde pancreatography, and were followed-up by regular examinations once or twice a year. Serial changes of the maximum cystic diameter and the appearance of mural nodules were studied during the observation periods ranging from 14 to 148 months (median, 61 months). Results: Nine (11.0%) of 82 patients exhibited obvious progression of cystic dilatation (median, 59 months). Of these nine patients with cystic enlargement, six continued with regular follow-up examinations. Three cases under- went surgical resection, and were pathologically diag- nosed as adenoma in two and borderline in one. Four patients (4.9%) showed newly developed mural nodules in dilated branch ducts (median, 105 months). Histological analysis revealed three cases classified as adenoma and one as carcinoma in situ. None of the remaining 69 patients (84.1%) showed any changes in dilated branch ducts (median, 57 months). Conclusions: Most branch duct IPMNs without mural nodules remained unchanged during long-term follow-up. Although follow-up with careful examination is required to detect newly developed mural nodules in dilated branch ducts, branch duct IPMNs without mural nodules can be followed-up without surgery. Intraductal papillary-mucinous neoplasm (IPMN) of the pancreas is a relatively new tumour entity that has unique clinicopathological features. 1–7 They are defined as an intraductal papillary growth of neoplastic columnar cells producing mucin that arise in the main pancreatic duct or its major branches. These neoplasms are characterised by variable biological behaviour and are classified as adenoma, borderline and carcinoma, the last category including both in situ and invasive varieties. 8 Although current thinking is that IPMNs have the potential to be malignant, 9 it is not known whether all IPMNs have malignant potential or what the time course of progression may be. IPMNs can be subdivided into ‘‘main duct’’ and ‘‘branch duct’’ types depending on the location of the lesion in the main pancreatic duct or the side branch, respectively. 810 There are significant differ- ences in the prevalence of cancer between main duct IPMNs and branch duct IPMNs, ranging from 57% to 92% and 6% to 46%, respectively. 9 11–15 The largest published series on patients with main duct IPMNs showed that approximately 70% are symptomatic, 60% had carcinoma and 46% had invasive carcinoma. 9 In contrast to main duct IPMNs, most branch duct IPMNs are asympto- matic and it is believed that the risk of malignancy is low in cystic lesions ,30 mm in size. 14 15 Therefore, the classification of IPMNs has sub- stantial value in determining the management strategy for this neoplasm. The majority of IPMNs are branch duct IPMNs, which are being diagnosed with increasing fre- quency. Despite frequent reporting, management of branch duct IPMNs has been controversial. The treatment controversy is based on the fact that IPMNs contain a wide range of histological findings from apparently benign to overtly malig- nant, and accurate preoperative prediction of malignancy is not possible by imaging modalities. Recently, it has been reported that one of the acceptable predictive signs of malignancy for branch duct IPMNs is the presence of mural nodules or protruding lesions in dilated branch ducts. 15–20 Therefore, branch duct IPMNs without mural nodules seem to be less aggressive compared with those with mural nodules or main duct IPMNs, and may possibly be followed-up conser- vatively. However, there is no clear consensus on how best to manage branch duct IPMNs without mural nodules. Understanding the natural history of branch duct IPMNs without mural nodules would allow us to improve management strategies for this neoplasm. In this study, the natural history of branch duct IPMNs without mural nodules during long-term follow-up was studied prospec- tively. METHODS Patients Eighty-two consecutive patients with branch duct IPMNs attending the medical gastroenterological units of our institution: Department of Gastroenterology, Asahikawa Medical College, Asahikawa, between 1990 and the end point of this study (December 2006), who fulfilled the diagnotic criteria of branch duct IPMN cited below, were included in the study. Pancreatic cancer Gut 2008;57:339–343. doi:10.1136/gut.2007.129684 339 on 11 August 2008 gut.bmj.comDownloaded from Diagnosis of branch duct IPMNs was based on the pathognomonic findings of endoscopic retrograde pancreato- graphy (ERP) 21 —that is, communication between the cyst and the main pancreatic duct (MPD), and the presence of mucin, as indicated by filling defects in the pancreatic duct—and was confirmed by ERP in all cases at diagnosis of branch duct IPMNs. To exclude mucinous cystic tumours of the pancreas or pseudocysts, characteristic findings of imaging studies, a grape- like multilocular cystic lesion communicating with the MPD was confirmed by CT scan, magnetic resonance cholangiopan- creatography (MRCP) and endoscopic ultrasonography (EUS) in all cases. The maximum diameter of the dilated branch duct and MPD was measured by EUS. Absence of mural nodules in dilated branch ducts was diagnosed by EUS in combination with MRCP and CT. To exclude pancreatic intraepithelial neoplasia, the size of IPMNs had to be .1 cm. 9 Follow-up Eighty-two branch duct IPMNs without mural nodules were selected for follow-up without surgical resection as outpatients. All followed-up patients gave consent for observation instead of surgical procedures. Imaging modalities including EUS in combination with CT scan and/or MRCP were performed once or twice a year. Serial changes of the maximum cystic diameter and the appearance of mural nodules were studied during the observation periods, ranging from 14 to 148 months (median, 61 months). Dilated branch ducts showing changes . 10 mm in diameter were defined as enlarged or reduced. Statistical analysis Statistical significance was analysed by Student t and Fisher exact x 2 tests. Differences were considered significant when the p value was ,0.05. RESULTS Patient characteristics The characteristics of 82 branch duct IPMN patients attending the medical gastroenterological unit of the Asahikawa Medical College are summarised in table 1. They consisted of 57 men and 25 women, with a median age of 68 years (range, 40–84 years). Only one case (1.2%) had recurrent pancreatitis; the remaining patients were asymptomatic. The median size of the dilated branch duct was 20 mm (range, 11–45 mm) at diagnosis of branch duct IPMNs. The location of the lesion was 49 (59.8%) in the head and 33 (40.2%) in the body to tail of the pancreas. The median maximum diameter of the MPD was 3 mm (range, 3–12 mm). The median follow-up period was 61 months (range, 14–148 months). Ten of 82 (12.2%) branch duct IPMNs had an initial dilated branch duct diameter of >30 mm, with a median diameter of 30 mm (range, 30–45 mm) (table 2). Fifty-four (65.9%) of those with branch duct IPMNs were older than 65 years in age, with a median age of 73 years (range, 65–84 years). There is no significant association between age and the initial size of the lesions in branch duct IPMN patients (p = 0.314). Clinical outcome of branch duct IPMNs without mural nodules Table 3 shows the clinical outcome of 82 branch duct IPMNs without mural nodules during long-term follow-up. Nine (11.0%) of 82 patients exhibited obvious progression of cystic dilatation after a median follow-up of 59 months (range, 14– 113 months). There were no patients with a reduction in size of dilated branch ducts. Four patients (4.9%) showed the appearance of mural nodules in dilated branch ducts after a median follow-up of 105 months (range, 45–148 months). None of the remaining 69 patients (84.1%) showed any changes in dilated branch ducts after a median follow-up of 57 months (range, 14–138 months). The characteristics of nine branch duct IPMNs with increased size of dilated branch ducts are shown in table 4. The nine cases consisted of one woman and eight men, with a median age of 74 years (range, 52–81 years) at diagnosis of branch duct IPMNs. Four (44.4%) of these nine patients had a MPD diameter of >7 mm. Cystic enlargement was observed between 14 and 113 months (median, 59 months) after the diagnosis of branch duct IPMNs. Although one patient had recurrent pancreatitis (patient 9), the remainder were asymptomatic. Of nine patients with cystic enlargement, six continued with regular follow-up examinations. Three cases underwent surgical resection and the IPMNs were pathologically diagnosed as adenoma in two and borderline in one. The characteristics of the four patients with branch duct IPMNs with the appearance of mural nodules in dilated branch ducts are shown in table 5. They consisted of four men, with a median age of 62 years (range, 43–74 years) at diagnosis of branch duct IPMNs. All patients were asymptomatic. One patient had an MPD diameter of 12 mm (patient 1). Mural nodules appeared between 45 and 148 months (median, 105 months) after diagnosis of branch duct IPMNs. Median maximum size of the mural nodules was 6.5 mm (range, 6– 8 mm). All of the patients with newly developed mural nodules underwent surgical resection. At histological analysis, three cases were classified as adenoma and one as carcinoma in situ. Table 6 shows a comparison of various clinical factors between patients with no cystic changes, with increased size of dilated branch ducts and with the appearance of mural nodules. The latest size of dilated branch ducts with the appearance of mural nodules was significantly larger than those without cystic changes, but not statistically different from those with cystic enlargement. The MPD diameter in the Table 1 Characteristics of the 82 patients with branch duct IPMNs without mural nodules Branch duct IPMNs without mural nodules (n = 82) Median age (years) (range) 68 (40–84) Male:female 57:25 Asymptomatic (%) 81 (98.8%) Median size of dilated branch duct (mm) (range) 20 (11–45) Median diameter of MPD (mm) (range) 3 (3–12) Location (%) Head 49 (59.8%) Body–tail 33 (40.2%) Median follow-up periods (months) (range) 61 (14–148) IPMN, intraductal papillary-mucinous neoplasm; MPD, main pancreatic duct. Table 2 Initial size of the dilated branch duct of the pancreas in relation to age Initial size of the dilated branch duct Age (years) ,65 (%) >65 (%) ,30 mm 26 (92.8) 46 (85.2) >30 mm 2 (7.2) 8 (14.8) Total 28 (100) 54 (100) There is no significant association between age and the initial size of the dilated branch duct (p = 0.314). Pancreatic cancer 340 Gut 2008;57:339–343. doi:10.1136/gut.2007.129684 on 11 August 2008 gut.bmj.comDownloaded from patients without cystic changes was significantly narrower than those with cystic enlargement or with the appearance of mural nodules. The time of follow-up in patients with appearance of mural nodules was significantly longer than those without cystic changes, but not statistically different from those with cystic enlargement. There were no significant differences in age, gender, location or initial size of the dilated branch duct between patients with cystic size changes and patients with the appearance of mural nodules. DISCUSSION Branch duct IPMN has been increasingly recognised and is now being diagnosed with increasing frequency. Many of these patients are elderly and asymptomatic. The majority of these lesions are believed to be premalignant, and the only curative treatment is surgical resection. 22 Despite the more frequent reporting of branch duct IPMN, the natural history of this disease is not well understood, and a number of controversies regarding its treatment persist. The majority of branch duct IPMNs appear to have no apparent mural nodules; however, little precise information is available on the natural history of branch duct IPMNs without mural nodules. Although current thinking is that all IPMNs have the potential to be malignant, 9 the frequency and rate of progres- sion to carcinoma in situ and invasive carcinoma are not known and may be different for branch duct IPMNs with and without mural nodules. It is clear that branch duct IPMN has a more favourable prognosis than standard ductal pancreatic adenocar- cinoma 23 ; however, the factors that determine outcome in these patients are not well understood. This is the first report demonstrating the evidence that the absence of mural nodules may be an important factor in determining a conservative management strategy for this tumour, as most branch duct IPMNs without mural nodules remained unchanged during long-term follow-up. Our data emphasise that branch duct IPMNs without mural nodules can be followed-up with careful examination to detect newly developed mural nodules in the dilated branch duct. The advantages of our study include a prospective study design, a near complete follow-up with a median of 61 months, and a much larger sample size of branch duct IPMNs than in previous studies. 24–29 In this study, 69 (84.1%) of 82 branch duct IPMN patients without mural nodules showed no changes in the dilated branch duct during follow-up lasting 14–138 months (median, 57 months) after diagnosis of branch duct IPMNs, whereas progression of branch duct IPMNs was found in 13 patients (15.9%) during follow-up lasting 14–148 months (median, 67 months). Of 13 patients exhibiting progression of IPMNs, nine patients (69.2%) had cystic enlargement alone. Three cases underwent surgical resection and were pathologically diagnosed as adenoma in two and borderline in one. Of four patients with newly developed mural nodules who underwent surgical resection, histological analysis showed that three cases were classified as adenoma and one as carcinoma in situ. Importantly, our study demonstrated that there was no invasive carcinoma in surgically resected specimens of branch duct IPMNs without mural nodules that had an increase in dilated branch duct size or the appearance of mural nodules. These findings suggest that close observation with careful attention to the appearance of mural nodules or cystic enlargement will obviate unnecessary surgery. However, the presence of mural nodules should be considered to be an indication for surgery in order to avoid the wrong treatment, because mural nodules have been reported to be indicative of malignancy in branch duct IPMNs, 15–20 and the natural history of branch duct IPMNs with mural nodules is not understood. In the past, several authors have noted that a cyst diameter of >30 mm suggests malignancy in branch duct IPMNs. 30 31 In this study, the 82 branch duct IPMN patients without mural nodules included 10 patients (12.2%) with a cystic size of >30 mm in diameter. Among them, two patients (20%) showed cystic enlargement alone and one (10%) had the appearance of a mural nodule, at 64.9 and 60.3 months on average after diagnosis of branch duct IPMNs, respectively. At pathological analysis, two cases were classified as adenoma and one as borderline. The remaining seven patients (70%) remained unchanged during the follow-up lasting 21–50 months (median, 30 months). In our experience, therefore, cystic lesions of >30 mm in diameter did not correlate well with cystic Table 3 Clinical outcome of branch duct IPMNs without mural nodules Clinical outcome Branch duct IPMNs without mural nodules (%) Size of dilated branch duct* No change 69 (84.1) Reduced 0 (0) Enlarged 9 (11.0){ Appearance of mural nodules 4 (4.9){ Total 82 (100) *Branch ducts showing changes .10 mm were defined as enlarged or reduced. {Three cases underwent surgery; the remaining six cases continued with regular follow-up examinations only. {All cases underwent surgery. IPMN, intraductal papillary-mucinous neoplasm Table 4 Characteristics of the nine patients with branch duct IPMNs with increased size of the dilated branch duct during follow-up Patient number Age* (years) Sex Location Dilated branch duct Diameter of MPD (mm) Duration of follow-up (months) Treatment Histology Initial size (mm) Latest size (mm) 1 67 M Head 16 35 3 106 Follow-up – 2 74 M Body 15 30 3 59 Follow-up – 3 74 M Head 30 40 10 113 Follow-up – 4 76 M Body–tail 16 26 3 19 Follow-up – 5 76 M Head 20 35 3 92 Follow-up – 6 81 F Head 21 37 3 48 Follow-up – 7 55 M Body 15 25 8 79 DP Adenoma 8 72 M Body 18 28 10 54 DP Adenoma 9 52 M Head 32 45 8 14 PpPD Borderline *Age at initial diagnosis of branch duct IPMN DP, distal pancreatectomy; F, female; IPMN, intraductal papillary-mucinous neoplasm; M, male; PpPD, pylorus-preserving pancreaticoduodenectomy. Pancreatic cancer Gut 2008;57:339–343. doi:10.1136/gut.2007.129684 341 on 11 August 2008 gut.bmj.comDownloaded from enlargement or the appearance of mural nodules. A similar observation was made by Chari et al. 32 In their study, 73 non- invasive IPMNs had an average diameter of 52 mm, whereas 40 invasive IPMNs had an average diameter of 66 mm. Thus, these data suggest that the size of a branch duct IPMN alone cannot be used to determine the treatment strategy. Several authors reported that a dilated MPD of >7 mm may predict malignancy of branch duct IPMNs in studies based on pathological analysis of surgically resected pancreas. 24–27 In this study, the mean maximum diameter of the MPD in branch duct IPMNs without cystic size changes was significantly narrower than those with the appearance of mural nodules or enlarge- ment of the dilated branch duct. Eleven (13.4%) of 82 patients had a dilated MPD of >7 mm, and six of these (54.5%) showed progression of branch duct IPMN during follow-up lasting 14– 148 months (median, 73 months). Furthermore, all three cases which had a MPD diameter of >10 mm showed cystic enlargement in two and the appearance of mural nodules in one. Thus, our follow-up data support the previous reports 24–27 and suggest that a dilated MPD of >7 mm may also predict the progression of branch duct IPMNs without mural nodules. In this study, 54 (65.9%) branch duct IPMN patients were 65 years or older. Among them, eight patients (14.8%) showed cystic enlargement in six and the appearance of mural nodules in two. Of 28 patients ,64 years old, five patients (17.9%) showed cystic enlargement in two and appearance of mural nodules in three. The mean age of those with branch duct IPMNs without cyst size changes at diagnosis of IPMNs was not significantly less than those with the appearance of mural nodules or enlargement of the dilated branch duct. In addition, the mean follow-up period of branch duct IPMNs without cyst size changes was not shorter than those with the appearance of mural nodules or enlargement of the dilated branch duct. Thus, these data suggest that age may not be a predictive factor for progression of branch duct IPMNs without mural nodules. Quality of life must certainly be taken into account in electing to perform surgery for branch duct IPMNs in elderly patients, especially with very old patients or those with impairments, because the operation involves a high level of morbidity. In conclusion, the current study demonstrated the long-term follow-up results of branch duct IPMN patients without mural nodules. The absence of mural nodules supports a conservative management policy without surgery in branch duct IPMNs, although follow-up with careful examination is required to detect the appearance of mural nodules in dilated branch ducts. It is recommended that careful attention should be paid to the presence or absence of mural nodules in order to determine the treatment strategy for branch duct IPMNs. Competing interests: None. REFERENCES 1. Loftus EV Jr, Olivares-Pakzad BA, Batts KP, et al. Intraductal papillary-mucinous tumors of the pancreas: clinicopathologic features, outcome, and nomenclature. Members of the Pancreas Clinic, and Pancreatic Surgeons of Mayo Clinic. Gastroenterology 1996;110:1909–18. 2. Azar C, Van de Stadt J, Rickaert F, et al. Intraductal papillary mucinous tumours of the pancreas. Clinical and therapeutic issues in 32 patients. Gut 1996;39:457–64. 3. Rivera JA, Fernandez-del Castillo C, Pins M, et al. 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Table 5 Characteristics of the four patients with branch duct IPMNs with the appearance of mural nodules in the dilated branch duct during follow-up Patient number Age* (year) Sex Location Dilated branch duct Size of mural nodules (mm) Diameter of MPD (mm) Duration of follow-up (months) Treatment Histology Initial size (mm) Latest size (mm) 1 43 M Head 20 30 7 12 67 PpPD Adenoma 2 61 M Head 15 32 6 5 143 PpPD Carcinoma in situ 3 63 M Tail 20 65 8 9 148 DP Adenoma 4 74 M Body 30 30 6 4 45 DP Adenoma *Age at initial diagnosis of branch duct IPMN. DP, distal pancreatectomy; IPMN, intraductal papillary-mucinous neoplasm; M, male; PpPD, pylorus-preserving pancreaticoduodenectomy. Table 6 Comparison of clinical factors between clinical outcomes Size of dilated branch duct Appearance of mural nodules (SD) No change (SD) Enlarged (SD) Age (years) 67.8 (8.8) 69.7 (9.9) 60.3 (12.8) Male:female 45:24 8:1 4:0 Dilated branch duct (mm) Initial size 19.1 (6.7) 20.3 (6.4) 21.3 (6.3) Latest size 19.2 (6.9)*{ 33.4 (6.7* 39.3 (17.2){ Location (head:body–tail) 42:27 5:4 2:2 Initial diameter of MPD (mm) 3.7 (1.5){1 5.7 (3.2){ 7.5 (3.7)1 Time of follow-up (months) 62.1 (35.7)" 64.9 (35.5) 100.8 (52.5)" *p,0.001; {p,0.001; {p,0.01; 1p,0.001; "p,0.05. MPD, main pancreatic duct. Pancreatic cancer 342 Gut 2008;57:339–343. doi:10.1136/gut.2007.129684 on 11 August 2008 gut.bmj.comDownloaded from 18. Yanagisawa A, Ohashi K, Hori M, et al. Ductectatic-type mucinous cystadenoma and cystadenocarcinoma of the human pancreas: a novel clinicopathological entity. Jpn J Cancer Res 1993;84:474–9. 19. Sugiyama M, Atomi Y. 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Natural history of pancreatic intraductal papillary mucinous tumor of branch duct type: follow-up study by magnetic resonance cholangiopancreatography. J Comput Assist Tomogr 2004;28:117–22. 26. Wakabayashi T, Kawaura Y, Morimoto H, et al. Clinical management of intraductal papillary mucinous tumors of the pancreas based on imaging findings. Pancreas 2001;22:370–7. 27. Yamaguchi K, Sugitani A, Chijiiwa K, et al. Intraductal papillary-mucinous tumor of the pancreas: assessing the grade of malignancy from natural history. Am Surg 2001;67:400–6. 28. Levy P, Jouannaud V, O’Toole D, et al. Natural history of intraductal papillary mucinous tumors of the pancreas: actuarial risk of malignancy. Clin Gastroenterol Hepatol 2006;4:460–8. 29. Salvia R, Crippa S, Falconi M, et al. Branch-duct intraductal papillary mucinous neoplasms of the pancreas: to operate or not to operate? Results of a prospective protocol on the management of 109 consecutive patients. Gut 2006. 30. Sugiyama M, Atomi Y, Kuroda A. Two types of mucin-producing cystic tumors of the pancreas: diagnosis and treatment. Surgery 1997;122:617–25. 31. Obara T, Maguchi H, Saitoh Y, et al. [Mucin-producing tumor of the pancreas: surgery or follow-up?]. Nippon Shokakibyo Gakkai Zasshi 1994;91:66–74. 32. Chari ST, Yadav D, Smyrk TC, et al. Study of recurrence after surgical resection of intraductal papillary mucinous neoplasm of the pancreas. Gastroenterology 2002;123:1500–7. Robin Spiller, editor Double lumen duodenum in a patient with melaena CLINICAL PRESENTATION A previously healthy 40-year-old woman came to our emer- gency department because of acute epigastric and tarry stools. Her vital signs were stable, and physical examination did not disclose other abnormalities. The blood sampling showed a normal level of haemoglobin and normal coagulation profile. Panendoscopy was performed under the impression that upper gastrointestinal haemorrhage was present, and there was no definite abnormality in the oesophagus and stomach except a double lumen identified in the second portion of the duodenum (fig 1). QUESTION What is your diagnosis? See page 364 for answers K-L Liu, 1 Y-M Tsang, 1 J-T Lin, 2 H-P Wang 3 1 Department of Medical Imaging, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan; 2 Department of Internal Medicine, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan; 3 Department of Emergency Medicine, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan Correspondence to: Dr. Hsiu-Po Wang, Department of Emergency Medicine, National Taiwan University Hospital, No. 7, Chung-Shan South Road, Taipei, Taiwan; wanghp@ntu.edu.tw Competing interests: None. Gut 2008;57:343. doi:10.1136/gut.2006.115311 Figure 1 Panendoscopy shows a double lumen in the second portion of the duodenum. Editor’s quiz: GI snapshot Pancreatic cancer Gut March 2008 Vol 57 No 3 343 on 11 August 2008 gut.bmj.comDownloaded from . results without mural nodules: long-term follow- up papillary- mucinous neoplasms of the pancreas Natural history of branch duct intraductal http://gut.bmj.com/cgi/content/full/57/3/339 Updated. Although branch duct intraductal papillary- mucinous neoplasms (IPMNs) of the pancreas without mural nodules are frequently observed in asymptomatic subjects, the natural history of these lesions. long-term follow- up. Although follow- up with careful examination is required to detect newly developed mural nodules in dilated branch ducts, branch duct IPMNs without mural nodules can be followed-up