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The Use of Pancreatoscopy in the Diagnosis of Intraductal Papillary Mucinous Tumor Lesions of the Pancreas
CLINICAL GASTROENTEROLOGY AND HEPATOLOGY 2005;3:S53–S57
The Use of Pancreatoscopy in the Diagnosis of Intraductal Papillary Mucinous Tumor Lesions of the Pancreas KENJIRO YASUDA, MUNEHIRO SAKATA, MOOSE UEDA, KOJI UNO, and MASATSUGU NAKAJIMA Department of Gastroenterology, Kyoto Second Red Cross Hospital, Kyoto, Japan
The diagnosis of intraductal papillary mucinous tumor (IPMT) can be performed under the direct visualization of peroral pancreatoscopy (PPS), although the visible field with PPS is limited and endoscopic accessories cannot be easily applied. PPS is useful in cases with IPMT not only for the main duct lesions but also for some of the branch lesions that can be shown through the dilated branch duct. PPS is useful for diagnosing IPMT because histologic diagnosis is possible from biopsy materials obtained by PPS or with radiograph guidance. Histologic findings can be suspected from the appearance and degree of the protrusion of the lesions in the cystic lesion or in the main duct. Thirty patients with IPMT were resected and confirmed histologically. Among them, 26 cases were examined by PPS. Detection rates of the 12 cases with polypoid tumor greater than 3 mm were 67% by PPS, 92% by endoscopic ultrasonography, and 100% by intraductal ultrasonography. Among the 6 cases of adenocarcinoma, 4 cases showed a tumor mass greater than 10 mm.
eroral pancreatoscopy (PPS), which has been developed from small-caliber endoscopy, involves introducing a scope directly into the pancreatic duct to observe the surface of the duct. The PPS system is performed via the accessory channel of a standard duodenoscope (mother scope). The small PPS endoscope (baby scope) is inserted through the working channel of the duodenoscope into the pancreatic duct via the papilla of Vater with or without endoscopic sphincterotomy. Because the diameter of the pancreatic duct is smaller than the bile duct, the diameter of the baby scope should be smaller and the performance of the baby scope is limited. PPS can be used for the differential diagnosis of pancreatic cancer and pancreatitis endoscopically and for obtaining biopsies. PPS also is useful in the removal of pancreatic stones. Intraductal papillary mucinous tumor (IPMT), also known as intraductal papillary mucinous neoplasm of the pancreas, is characterized by proliferation of the epithelium of the pancreatic duct with various degrees of mucin hypersecretion, a dilated main pancreatic duct
P
and widely opened papilla of Vater, a feature that facilitates direct cannulation of the papilla by PPS.
Imaging Modalities for Pancreatic Lesions Imaging diagnostic tools for pancreatic lesions have different characteristics, and potential endoscopic retrograde cholangiopancreatography (ERCP) and magnetic resonance cholangiopancreatography can show the pancreaticobiliary ductal system. ERCP provides access to therapy by endoscopic sphincterotomy or a transpapillary cytology or biopsy examination. On the other hand, ultrasonography, computed tomography, magnetic resonance imaging, endoscopic ultrasonography (EUS), and intraductal ultrasonography (IDUS) are useful to detect pancreatic lesions and staging of malignant tumors. Histopathologic study can be performed by pancreatic juice cytology fineneedle aspiration cytology, or biopsy examination via PPS. The use of pancreatoscopy is dependent on the size of scope and the diameter of the working channel. Endoscopes range from 4.5 mm external diameter with 1.7 mm diameter working channel to .9 mm external diameter without a working channel. Durability is a concern when using PPS because of the fragility of the small baby-scope optics. Common indications for PPS include evaluation of pancreatic duct strictures or carcinoma, biopsy under direct view and differentiation of filling defect suggestive of stones or a tumor in the pancreatic duct.1– 4 Figure 1 shows the recent model of the electronic baby scope, which has a working channel for the forceps and a diameter of 3 mm. This model has up and down Abbreviations used in this paper: ERCP, endoscopic retrograde cholangiopancreatography; ERP, endoscopic retrograde pancreatography; EUS, endoscopic ultrasonography; IDUS, intraductal ultrasonography; IPMT, intraductal papillary mucinous tumor; PPS, peroral pancreatoscopy. © 2005 by the American Gastroenterological Association 1542-3565/05/$30.00 PII: 10.1053/S1542-3565(05)00263-6
S54
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CLINICAL GASTROENTEROLOGY AND HEPATOLOGY Vol. 3, No. 7
Figure 1. Recent model of pancreatoscope.
bending functions, but the bending range is not satisfactory because of the thin and long scope shaft.
Clinical and Histologic Findings of Intraductal Papillary Mucinous Tumor of the Pancreas IPMT usually is detected by conventional ultrasonography showing the dilated main pancreatic duct or cystic lesion. At ERCP, there is a widely enlarged orifice of the papilla of Vater with the excretion of mucin and dilatation of the pancreatic ductal system with or without the cystic lesion (Figures 2 and 3). By imaging diagnostic tools, the appearance of IPMT is divided into 2 categories. One is the main duct type and the other is the branch duct type. In addition, a combined type of lesion often is observed Table 1. ERCP Findings of IPMT Cases
Adenocarcinoma (n ⫽ 6) Adenoma (n ⫽ 20) Hyperplasia (n ⫽ 4) Total (n ⫽ 30) MPD, main pancreatic duct.
Enlarged orifice of papilla
MPD ⬎5 mm
Number with cystic lesion
5 11 3 19 (63%)
6 17 3 26 (87%)
3 16 3 22 (73%)
as the lesion expands along the pancreatic duct epithelium. Although it is not easy to obtain a histologic diagnosis, the correct diagnosis of IPMT is very important for selecting the preferred treatment or for selecting patients for follow-up. Histopathologically, the lesions vary from hyperplasia to adenoma to adenocarcinoma. Both hyperplastic and adenomatous changes are considered premalignant; however, the need for pancreatic resection in such patients is poorly defined.
Peroral Pancreatoscopy in Cases With Intraductal Papillary Mucinous Tumor Pancreatoscopy can provide more precise information in IPMT because it is possible to observe the surface of the pancreatic duct and to obtain a biopsy specimen for pathologic study. When located in the main pancreatic duct, the lesion can be seen directly as Table 2. Height of Tumor of IPMT Measured by EUS and IDUS and Confirmed Histologically
Adenocarcinoma (n ⫽ 6) Adenoma (n ⫽ 20) Hyperplasia (n ⫽ 4)
⬎10 mm
⬎3 mm
⬎1 mm
⬍1 mm
4 -
2 6 -
12 1
2 3
July Supplement 2005
PANCREATOSCOPY FOR PANCREATIC IPMT LESIONS
Table 3. PPS Findings of IPMT No. of cases Adenocarcinoma
Adenoma
Hyperplasia
6
16
4
S55
Table 5. Positive Results of Cytology and Biopsy PPS Findings
Cases (%)
Papillary tumor Redness and proliferation of blood vessels Papillary tumor Redness and proliferation of blood vessels Fish-egg–like appearance Fish-egg–like appearance Redness and proliferation of blood vessels
6 (100) 5 (83) 2 (13) 5 (31) 5 (31) 1 (25) 0 (0)
a villiform stricture, which is a fish-egg–like lesion in the lumen of the pancreatic duct (see Figure 2B).
Case Series Thirty patients with IPMT had laparotomy and the tumors were resected and confirmed histologically. Among them, there were 6 cases of adenocarcinoma, 20 cases of adenoma, and 4 cases of hyperplasia. ERCP showed the enlarged orifice of papilla of Vater in 19 of 30 cases (63%), the dilated main pancreatic duct in 26 cases (87%), and a cystic lesion in 22 cases (73%) (Table 1). We tabulated the histologic nature by the size of the tumor masses of IPMT, as measured by EUS and IDUS (Table 2). Protruding lesions greater than 10 mm were adenocarcinomas. No carcinoma was found in the lesions that were smaller than 3 mm in height. PPS was performed in 26 cases and characteristic findings such as a papillary tumor, redness and proliferation of blood vessels, or fish-egg–like appearance (Figure 2B) were observed in 19 lesions (Table 3). Among them, a papillary tumor was observed in 8 cases, including 6 of 6 cases of adenocarcinoma and 2 of 16 cases of adenoma. The sensitivity for the detection of polypoid lesions greater than 3 mm compared with histology was 67% by PPS, 92% by EUS, and 100% by IDUS (Table 4). These lesions were shown poorly by transabdominal ultrasonography, computed tomography, and magnetic resonance imaging.
Radiographs
Biopsy Cytology (n ⫽ 11) (n ⫽ 18) Adenocarcinoma (n ⫽ 6) Adenoma (n ⫽ 20) Hyperplasia (n ⫽ 4) Sensitivity Specificity
Biopsy (n ⫽ 9)
Cytology (n ⫽ 28)
3/6 5/5
2/4 14/14
3/5 4/4
2/5 23/23
50% 100%
50% ¢
60% ¢
40% ¢
Other than tumor size and PPS-directed biopsy examination, no other feature was capable of distinguishing adenomas from carcinomas. Even examination of biopsies taken under direct view of the baby scope or pancreatic juice cytology were positive in only 50% of adenocarcinomas (Table 5). To diagnose the longitudinal extent of main duct IPMT, it is necessary to evaluate the surface lesion in the main pancreatic duct and the cystic lesion. The lesion in the main pancreatic duct can be observed by ERCP, EUS, IDUS, and PPS. Among them, PPS has a high diagnostic accuracy and is useful to detect the extent of lesions and to decide the extent of the surgical resection. The branch-type lesion shows multiloculated cystic lesions with or without a nodular tumor in the cyst. These lesions are shown by cross-sectional imaging modalities such as ultrasonography, computed tomography, magnetic resonance imaging, EUS, and IDUS. In the 30 patients in our series, none had pancreatitis after PPS and other studies.
Conclusions PPS is a useful method to evaluate IPMT, although there are some limitations in the accuracy and ability to perform a biopsy examination. Rarely, PPS can observe the lesions in the branch duct. In addition, PPS is helpful to decide the extent of surgical excision. However, to evaluate the whole lesions, cross-imaging modalities such as EUS and IDUS are recommended (Figure 4), and hence these tests are complementary and aid the management of IPMT.
Table 4. Positive Finding Rates of Protruded Lesions Higher Than 3 mm by Imaging Modalities
Adenocarcinoma (n ⫽ 6) Adenoma (n ⫽ 6) Total (n ⫽ 12)
Ultrasonography
Computed tomography
Magnetic resonance
EUS
IDUS
PPS
3/6 0/6 3/12 (25%)
2/6 0/6 2/12 (16%)
1/2 0/3 1/5 (20%)
6/6 5/6 11/12 (92%)
4/4 5/5 9/9 (100%)
6/6 2/6 8/12 (67%)
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YASUDA ET AL
Figure 2. A case of adenoma in IPMT. (A) The endoscopic retrograde pancreatography (ERP) finding with the baby scope and cystic lesions in the pancreas. (B) PPS finding shows the protruded lesion with surrounding fish-egg–like surface. (C) Biopsy study revealed features consistent with adenoma.
CLINICAL GASTROENTEROLOGY AND HEPATOLOGY Vol. 3, No. 7
Figure 3. A case of adenocarcinoma in IPMT. (A) ERP showed a round filling defect at the head of the pancreas. (B) PPS showed the polypoid lesion in the pancreatic duct. (C) Biopsy study showed features suggestive of adenocarcinoma.
July Supplement 2005
PANCREATOSCOPY FOR PANCREATIC IPMT LESIONS
S57
Figure 4. A case of adenoma in IPMT. (A) ERP showed a cystic lesion with a dilated main pancreatic duct, and the orifice of the papilla of Vater was enlarged by hypersecretion of mucin. (B) Pancreatoscopy shows the granular lesion. (C) EUS shows a multiloculated cystic lesion with a protruded lesion (arrow). (D) IDUS shows the cystic lesion with papillary tumor (arrow, left) and a protruded lesion at the main pancreatic duct (arrow), which corresponds to the protruded lesion observed by PPS.
References 1. Nakajima M, Akasaka Y, Fukumoto K, et al. Peroral cholangiopancreatoscopy (PCPS) under duodenoscopic guidance. Am J Gastroenterol 1976;66:241–247. 2. Riemann JF, Kohler B. Endoscopy of the pancreatic duct; value of different endoscope types. Gastrointest Endosc 1993;39:367–370. 3. Mizuno S, Nakajima M, Yasuda K, et al. Shape memory alloy catheter
system for peroral pancreatoscopy using ultrathin-caliber endoscope. Endoscopy 1994;26:676 – 680. 4. Kozarek RA. Direct pancreatoscopy. Gastrointest Endosc Clin N Am 1995;5:259 –267.
Address requests for reprints to: Kenjiro Yasuda, MD, Department of Gastroenterology, Kyoto Second Red Cross Hospital, Kyoto, Japan.
The Use of Pancreatoscopy in the Diagnosis of Intraductal Papillary Mucinous Tumor Lesions of the Pancreas KENJIRO YASUDA, MUNEHIRO SAKATA, MOOSE UEDA, KOJI UNO, and MASATSUGU NAKAJIMA Department of Gastroenterology, Kyoto Second Red Cross Hospital, Kyoto, Japan
The diagnosis of intraductal papillary mucinous tumor (IPMT) can be performed under the direct visualization of peroral pancreatoscopy (PPS), although the visible field with PPS is limited and endoscopic accessories cannot be easily applied. PPS is useful in cases with IPMT not only for the main duct lesions but also for some of the branch lesions that can be shown through the dilated branch duct. PPS is useful for diagnosing IPMT because histologic diagnosis is possible from biopsy materials obtained by PPS or with radiograph guidance. Histologic findings can be suspected from the appearance and degree of the protrusion of the lesions in the cystic lesion or in the main duct. Thirty patients with IPMT were resected and confirmed histologically. Among them, 26 cases were examined by PPS. Detection rates of the 12 cases with polypoid tumor greater than 3 mm were 67% by PPS, 92% by endoscopic ultrasonography, and 100% by intraductal ultrasonography. Among the 6 cases of adenocarcinoma, 4 cases showed a tumor mass greater than 10 mm.
eroral pancreatoscopy (PPS), which has been developed from small-caliber endoscopy, involves introducing a scope directly into the pancreatic duct to observe the surface of the duct. The PPS system is performed via the accessory channel of a standard duodenoscope (mother scope). The small PPS endoscope (baby scope) is inserted through the working channel of the duodenoscope into the pancreatic duct via the papilla of Vater with or without endoscopic sphincterotomy. Because the diameter of the pancreatic duct is smaller than the bile duct, the diameter of the baby scope should be smaller and the performance of the baby scope is limited. PPS can be used for the differential diagnosis of pancreatic cancer and pancreatitis endoscopically and for obtaining biopsies. PPS also is useful in the removal of pancreatic stones. Intraductal papillary mucinous tumor (IPMT), also known as intraductal papillary mucinous neoplasm of the pancreas, is characterized by proliferation of the epithelium of the pancreatic duct with various degrees of mucin hypersecretion, a dilated main pancreatic duct
P
and widely opened papilla of Vater, a feature that facilitates direct cannulation of the papilla by PPS.
Imaging Modalities for Pancreatic Lesions Imaging diagnostic tools for pancreatic lesions have different characteristics, and potential endoscopic retrograde cholangiopancreatography (ERCP) and magnetic resonance cholangiopancreatography can show the pancreaticobiliary ductal system. ERCP provides access to therapy by endoscopic sphincterotomy or a transpapillary cytology or biopsy examination. On the other hand, ultrasonography, computed tomography, magnetic resonance imaging, endoscopic ultrasonography (EUS), and intraductal ultrasonography (IDUS) are useful to detect pancreatic lesions and staging of malignant tumors. Histopathologic study can be performed by pancreatic juice cytology fineneedle aspiration cytology, or biopsy examination via PPS. The use of pancreatoscopy is dependent on the size of scope and the diameter of the working channel. Endoscopes range from 4.5 mm external diameter with 1.7 mm diameter working channel to .9 mm external diameter without a working channel. Durability is a concern when using PPS because of the fragility of the small baby-scope optics. Common indications for PPS include evaluation of pancreatic duct strictures or carcinoma, biopsy under direct view and differentiation of filling defect suggestive of stones or a tumor in the pancreatic duct.1– 4 Figure 1 shows the recent model of the electronic baby scope, which has a working channel for the forceps and a diameter of 3 mm. This model has up and down Abbreviations used in this paper: ERCP, endoscopic retrograde cholangiopancreatography; ERP, endoscopic retrograde pancreatography; EUS, endoscopic ultrasonography; IDUS, intraductal ultrasonography; IPMT, intraductal papillary mucinous tumor; PPS, peroral pancreatoscopy. © 2005 by the American Gastroenterological Association 1542-3565/05/$30.00 PII: 10.1053/S1542-3565(05)00263-6
S54
YASUDA ET AL
CLINICAL GASTROENTEROLOGY AND HEPATOLOGY Vol. 3, No. 7
Figure 1. Recent model of pancreatoscope.
bending functions, but the bending range is not satisfactory because of the thin and long scope shaft.
Clinical and Histologic Findings of Intraductal Papillary Mucinous Tumor of the Pancreas IPMT usually is detected by conventional ultrasonography showing the dilated main pancreatic duct or cystic lesion. At ERCP, there is a widely enlarged orifice of the papilla of Vater with the excretion of mucin and dilatation of the pancreatic ductal system with or without the cystic lesion (Figures 2 and 3). By imaging diagnostic tools, the appearance of IPMT is divided into 2 categories. One is the main duct type and the other is the branch duct type. In addition, a combined type of lesion often is observed Table 1. ERCP Findings of IPMT Cases
Adenocarcinoma (n ⫽ 6) Adenoma (n ⫽ 20) Hyperplasia (n ⫽ 4) Total (n ⫽ 30) MPD, main pancreatic duct.
Enlarged orifice of papilla
MPD ⬎5 mm
Number with cystic lesion
5 11 3 19 (63%)
6 17 3 26 (87%)
3 16 3 22 (73%)
as the lesion expands along the pancreatic duct epithelium. Although it is not easy to obtain a histologic diagnosis, the correct diagnosis of IPMT is very important for selecting the preferred treatment or for selecting patients for follow-up. Histopathologically, the lesions vary from hyperplasia to adenoma to adenocarcinoma. Both hyperplastic and adenomatous changes are considered premalignant; however, the need for pancreatic resection in such patients is poorly defined.
Peroral Pancreatoscopy in Cases With Intraductal Papillary Mucinous Tumor Pancreatoscopy can provide more precise information in IPMT because it is possible to observe the surface of the pancreatic duct and to obtain a biopsy specimen for pathologic study. When located in the main pancreatic duct, the lesion can be seen directly as Table 2. Height of Tumor of IPMT Measured by EUS and IDUS and Confirmed Histologically
Adenocarcinoma (n ⫽ 6) Adenoma (n ⫽ 20) Hyperplasia (n ⫽ 4)
⬎10 mm
⬎3 mm
⬎1 mm
⬍1 mm
4 -
2 6 -
12 1
2 3
July Supplement 2005
PANCREATOSCOPY FOR PANCREATIC IPMT LESIONS
Table 3. PPS Findings of IPMT No. of cases Adenocarcinoma
Adenoma
Hyperplasia
6
16
4
S55
Table 5. Positive Results of Cytology and Biopsy PPS Findings
Cases (%)
Papillary tumor Redness and proliferation of blood vessels Papillary tumor Redness and proliferation of blood vessels Fish-egg–like appearance Fish-egg–like appearance Redness and proliferation of blood vessels
6 (100) 5 (83) 2 (13) 5 (31) 5 (31) 1 (25) 0 (0)
a villiform stricture, which is a fish-egg–like lesion in the lumen of the pancreatic duct (see Figure 2B).
Case Series Thirty patients with IPMT had laparotomy and the tumors were resected and confirmed histologically. Among them, there were 6 cases of adenocarcinoma, 20 cases of adenoma, and 4 cases of hyperplasia. ERCP showed the enlarged orifice of papilla of Vater in 19 of 30 cases (63%), the dilated main pancreatic duct in 26 cases (87%), and a cystic lesion in 22 cases (73%) (Table 1). We tabulated the histologic nature by the size of the tumor masses of IPMT, as measured by EUS and IDUS (Table 2). Protruding lesions greater than 10 mm were adenocarcinomas. No carcinoma was found in the lesions that were smaller than 3 mm in height. PPS was performed in 26 cases and characteristic findings such as a papillary tumor, redness and proliferation of blood vessels, or fish-egg–like appearance (Figure 2B) were observed in 19 lesions (Table 3). Among them, a papillary tumor was observed in 8 cases, including 6 of 6 cases of adenocarcinoma and 2 of 16 cases of adenoma. The sensitivity for the detection of polypoid lesions greater than 3 mm compared with histology was 67% by PPS, 92% by EUS, and 100% by IDUS (Table 4). These lesions were shown poorly by transabdominal ultrasonography, computed tomography, and magnetic resonance imaging.
Radiographs
Biopsy Cytology (n ⫽ 11) (n ⫽ 18) Adenocarcinoma (n ⫽ 6) Adenoma (n ⫽ 20) Hyperplasia (n ⫽ 4) Sensitivity Specificity
Biopsy (n ⫽ 9)
Cytology (n ⫽ 28)
3/6 5/5
2/4 14/14
3/5 4/4
2/5 23/23
50% 100%
50% ¢
60% ¢
40% ¢
Other than tumor size and PPS-directed biopsy examination, no other feature was capable of distinguishing adenomas from carcinomas. Even examination of biopsies taken under direct view of the baby scope or pancreatic juice cytology were positive in only 50% of adenocarcinomas (Table 5). To diagnose the longitudinal extent of main duct IPMT, it is necessary to evaluate the surface lesion in the main pancreatic duct and the cystic lesion. The lesion in the main pancreatic duct can be observed by ERCP, EUS, IDUS, and PPS. Among them, PPS has a high diagnostic accuracy and is useful to detect the extent of lesions and to decide the extent of the surgical resection. The branch-type lesion shows multiloculated cystic lesions with or without a nodular tumor in the cyst. These lesions are shown by cross-sectional imaging modalities such as ultrasonography, computed tomography, magnetic resonance imaging, EUS, and IDUS. In the 30 patients in our series, none had pancreatitis after PPS and other studies.
Conclusions PPS is a useful method to evaluate IPMT, although there are some limitations in the accuracy and ability to perform a biopsy examination. Rarely, PPS can observe the lesions in the branch duct. In addition, PPS is helpful to decide the extent of surgical excision. However, to evaluate the whole lesions, cross-imaging modalities such as EUS and IDUS are recommended (Figure 4), and hence these tests are complementary and aid the management of IPMT.
Table 4. Positive Finding Rates of Protruded Lesions Higher Than 3 mm by Imaging Modalities
Adenocarcinoma (n ⫽ 6) Adenoma (n ⫽ 6) Total (n ⫽ 12)
Ultrasonography
Computed tomography
Magnetic resonance
EUS
IDUS
PPS
3/6 0/6 3/12 (25%)
2/6 0/6 2/12 (16%)
1/2 0/3 1/5 (20%)
6/6 5/6 11/12 (92%)
4/4 5/5 9/9 (100%)
6/6 2/6 8/12 (67%)
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YASUDA ET AL
Figure 2. A case of adenoma in IPMT. (A) The endoscopic retrograde pancreatography (ERP) finding with the baby scope and cystic lesions in the pancreas. (B) PPS finding shows the protruded lesion with surrounding fish-egg–like surface. (C) Biopsy study revealed features consistent with adenoma.
CLINICAL GASTROENTEROLOGY AND HEPATOLOGY Vol. 3, No. 7
Figure 3. A case of adenocarcinoma in IPMT. (A) ERP showed a round filling defect at the head of the pancreas. (B) PPS showed the polypoid lesion in the pancreatic duct. (C) Biopsy study showed features suggestive of adenocarcinoma.
July Supplement 2005
PANCREATOSCOPY FOR PANCREATIC IPMT LESIONS
S57
Figure 4. A case of adenoma in IPMT. (A) ERP showed a cystic lesion with a dilated main pancreatic duct, and the orifice of the papilla of Vater was enlarged by hypersecretion of mucin. (B) Pancreatoscopy shows the granular lesion. (C) EUS shows a multiloculated cystic lesion with a protruded lesion (arrow). (D) IDUS shows the cystic lesion with papillary tumor (arrow, left) and a protruded lesion at the main pancreatic duct (arrow), which corresponds to the protruded lesion observed by PPS.
References 1. Nakajima M, Akasaka Y, Fukumoto K, et al. Peroral cholangiopancreatoscopy (PCPS) under duodenoscopic guidance. Am J Gastroenterol 1976;66:241–247. 2. Riemann JF, Kohler B. Endoscopy of the pancreatic duct; value of different endoscope types. Gastrointest Endosc 1993;39:367–370. 3. Mizuno S, Nakajima M, Yasuda K, et al. Shape memory alloy catheter
system for peroral pancreatoscopy using ultrathin-caliber endoscope. Endoscopy 1994;26:676 – 680. 4. Kozarek RA. Direct pancreatoscopy. Gastrointest Endosc Clin N Am 1995;5:259 –267.
Address requests for reprints to: Kenjiro Yasuda, MD, Department of Gastroenterology, Kyoto Second Red Cross Hospital, Kyoto, Japan.