British Journal of Radiology 74 (2001),1074-1075 © 2001 The British Institute of Radiology
What the endoscopist saw
D Murray, MRCP, FRCR and
R Price, MRCP, FRCR, FRANZCR
Department of Interventional and Diagnostic Radiology, Royal Perth Hospital, Wellington Street, Box X2213 GPO, Perth, WA 6847, Australia
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Introduction
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A 54-year-old male presented with gradually increasing central abdominal pain over a 3-month period. Clinical examination and routine investigations, including liver function tests and amylase, were normal.
His subsequent CT (Figure 1
) and endoscopic retrograde cholangiopancreatography (ERCP) (Figure 2) are shown below. The endoscopist reported an unusual finding during performance of ERCP.
What did the endoscopist see and what is your diagnosis?
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Answer
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The endoscopist saw mucin extruding from a bulging papilla into the duodenal lumen. This finding at ERCP is virtually pathognomonic of an intraductal mucinous pancreatic tumour. ERCP (Figure 2
) showed a dilated pancreatic duct in continuity with a multilocular cystic mass within the pancreatic tail. Careful examination of the images showed several linear filling defects within the dilated duct representing mucus strands.
The enhanced abdominal CT (Figure 1) demonstrated multiple cysts in the tail of the pancreas. A dilated pancreatic duct was also seen on adjacent images. There was no calcification within the pancreas, and the biliary tree was unremarkable.
The patient underwent surgical resection of the pancreatic tail. The histology demonstrated several dysplastic foci and areas of malignant epithelial transformation. The patient remains well at follow-up.
Cystic masses of the pancreas are a heterogeneous group of both non-neoplastic inflammatory lesions and tumours with varying malignant potential. 80–90% of pancreatic cystic masses in adults are inflammatory pseudocysts and the restare neoplastic masses. Mucinous pancreatic tumours are divided into peripheral (cystadenoma, cystadenocarcinoma) and ductal tumours according to their site of origin.
Japanese authors were the first to suggest that mucin-secreting tumours characterized by dilated pancreatic ducts were separate entities from other pancreatic neoplasms. The abnormal mucin-secreting cells in the pancreatic duct may lie anywhere along a spectrum of benign to frankly malignant, and different histological grades frequently co-exist. Unfortunately, the condition is known by several synonyms, including mucinous ductal ectasia and ductectatic (mucinous) cystadenoma/carcinoma. The unifying term intraductal mucinous pancreatic tumour defines a primarily intraductal papillomatous tumour associated with excessive mucin secretion and resulting in progressive ductal dilatation or cyst formation [1]. Intraductal mucinous pancreatic tumours (IMPTs) are divided into those arising from the main pancreatic duct and those arising from a side branch, which is usually within the uncinate process. Main duct involvement may be segmental or diffuse. IMPTs can be difficult to distinguish radiologically from chronic pancreatitis, as there may be associated parenchymal atrophy and calcific deposits within the mucin secretions. Furthermore, IMPTs can be associated with recurrent acute pancreatitis and the two conditions may coexist.
Although the tumours generally follow a benign progressive course, early diagnosis before malignant local invasion occurs is important to enable curative tumour resection. Imaging features correlating with malignancy are the presence of a bulging papilla and large calibre pancreatic duct, the thickness of the cyst wall and the presence of mural nodules.
Fukukura et al [2] reported imaging findings during thin section (3–5 mm) helical CT in patients with proven IMPT. A cystic mass or dilation of the main pancreatic duct occurred in the majority of cases. A papilla bulging into the duodenum and papillary projections into the dilated pancreatic ducts were sometimes present.
ERCP is often conclusive, demonstrating direct communication of the lesion with the main pancreatic duct, as well as directly visualizing the bulging papilla and excess mucin. Thick mucin and the abnormal ampulla occasionally hinder attempts at complete opacification of the pancreatic ducts during ERCP. Aspiration of the mucus and the use of a balloon catheter may be beneficial in these cases.
MR cholangiopancreatography (MRCP) is an effective non-invasive technique for evaluating these patients and can demonstrate the papillary projections as well as the ductal communication [3]. It is particularly useful for demonstrating the entire ductal system in the presence of excessive intraductal mucin. Irie et al [4] reported its usefulness in demonstrating intraductal nodules or dilatation of the main pancreatic duct greater than 15 mm in differentiating benign from malignant IMPTs.
At ultrasound, echogenic mucin within the dilated ducts can be indistinguishable from the surrounding pancreatic parenchyma. Occasionally duct dilatation distal to a mucin obstruction may be seen. EUS may demonstrate complex cysts, papillary projections and dilatation of the main pancreatic duct. Diffuse hyperechoic thickening of the duct wall has also been described [5].
Received for publication November 7, 2000.
Accepted for publication November 27, 2000.
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References
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Procacci C, Megibow AJ, Carbognin G, Spoto E, Biasiutti C, Pistolesi GF. Intraductal papillary mucinous tumour of the pancreas: a pictorial essay. Radiographics 1999;19:1447–63.[Abstract/Free Full Text]
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Fukukura Y, Fujiyoshi F, Sasaki M, Inoue H, Yonezawa S, Nakajo M. Intraductal papillary mucinous tumors of the pancreas: thin-section helical CT findings. AJR 2000;174:441–7.[Abstract/Free Full Text]
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Fukukura Y, Fujiyoshi F, Sasaki M, Ichinari N, Inoue H, Kajiya Y, et al. HASTE MR cholangiopancreatography in the evaluation of intraductal papillary-mucinous tumours of the pancreas. J Comput Assist Tomogr 1999;23:301–5.[Medline]
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Irie H, Honda H, Aibe H, Kuroiwa T, Yoshimitsu K, Shinozaki K, et al. MR cholangiopancreatographic differentiation of benign and malignant intraductal mucin-producing tumours of the pancreas. AJR 2000;174:1403–8.[Abstract/Free Full Text]
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Gress F, Gottlieb K, Cummings O, Sherman S, Lehman G. Endoscopic ultrasound characteristics of mucinous cystic neoplasms of the pancreas. Am J Gastroenterol 2000;95:961–5.[Medline]
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