Biliary lesions associated with autoimmune pancreatitis.

BACKGROUND/AIMS: Characteristic radiological features of biliary lesions in patients with autoimmune pancreatitis (AIP) have not yet been identified. METHODOLOGY: Bile duct lesions and their relationships to other clinical findings were assessed in 43 AIP patients. RESULTS: Of the 43 AIP patients, 34 (79%) had bile duct stenosis. In all the 34 patients, the lower bile duct was involved; in 21 of these, only the lower bile duct was involved, and in 13 patients, there was widespread wall thickening of the middle and upper bile duct where stenosis was not obvious on cholangiography. Furthermore, 4 patients with extensive bile duct involvement also had stenosis of the intrahepatic bile duct. All patients with bile duct involvement had involvement of the head portion of the main pancreatic duct. None of the 6 patients with involvement of only the body and/or tail portion of the main pancreatic duct had bile duct involvement. Gallbladder wall thickening was more frequently noted in patients with extensive bile duct involvement (p < 0.01). Serum IgG4 levels were significantly more elevated in patients with extensive bile duct involvement (p < 0.05). CONCLUSIONS: AIP patients with extensive bile duct involvement characterized by widespread wall thickening of the bile duct may have more active disease.

Frequent and significant K-ras mutation in the pancreas, the bile duct, and the gallbladder in autoimmune pancreatitis.

OBJECTIVES: To assess the relationship between autoimmune pancreatitis (AIP) and pancreatic cancer, we analyzed K-ras mutation in the pancreatobiliary tissues of patients with AIP. METHODS: An analysis of K-ras mutation and an immunohistochemical study were performed on the pancreas of 8 patients with AIP and 10 patients with chronic alcoholic pancreatitis and on the common bile duct and the gallbladder of 9 patients with AIP. K-ras mutation was analyzed in the pure pancreatic juice from 3 patients with AIP. RESULTS: High-frequency K-ras mutation (2+ or 3+) was detected in the pancreas of all the 8 patients and in the pancreatic juice of the other 2 patients. The mutation in codon 12 of the ras gene was GAT in all the 10 patients. High-frequency K-ras mutation was detected in the common bile duct of 5 patients with AIP and in the gallbladder epithelium of 4 patients with AIP. The K-ras mutation was detected in the fibroinflammatory pancreas, the bile duct, and the gallbladder, with abundant infiltrating IgG4-positive plasma and Foxp3-positive cells of patients with AIP with elevated serum IgG4 levels. CONCLUSIONS: Significant K-ras mutation occurs most frequently in the pancreatobiliary regions of patients with AIP. Autoimmune pancreatitis may be a risk factor of pancreatobiliary cancer.

Endocrine cells in ampullary carcinoma.

BACKGROUND/PURPOSE: As ampullary carcinoma originates from four anatomical regions, it may have different behaviors depending on its origin. We documented the presence of endocrine cells found in ampullary carcinoma, and we studied the clinicopathological implications of their presence. METHODS: We immunohistochemically examined the presence of an endocrine component in 62 surgically resected specimens of ampullary carcinoma, and we studied the clinicopathological differences between endocrine component-positive cases and endocrine component-negative cases. RESULTS: Endocrine cells were detected in 16 cases (26%); 11 cases had many endocrine cells, and five cases had scattered endocrine cells. Serotonin-positive cells were detected in all 16 cases, in which six cases had many positive cells. Several somatostatin-positive cells were detected in three cases. Endocrine cells were detected in ampulloduodenal polypoid lesions (two cases) and ampullopancreaticobiliary ducts (14 cases). The histology of 15 of the 16 endocrine component-positive ampullary carcinomas was the intestinal type. Pancreatic invasion and lymph node involvement were observed less frequently in endocrine component-positive cases (P < 0.01). There were no significant differences with respect to immunoreactivity for carbohydrate antigen (CA) 19.9, carcinembryonic antigen (CEA), and p53 overexpression, and K-ras mutations. CONCLUSIONS: Endocrine component-positive ampullary carcinoma seemed to be derived from the ampullopancreaticobiliary common duct or the ampulloduodenum, and to behave less aggressively than endocrine component-negative carcinoma.

Metachronous Carcinomas of the Biliary Tract in a Patient Treated Three Times with Curative Surgery.

We here report on a case of metachronous multicentric carcinomas of the biliary tract treated 3 times with curative surgery over 23 years. A 28-year-old woman underwent cholecystectomy because of papillary carcinoma of the gallbladder. After 17 years, 3 carcinomas developed in the biliary tract: intrahepatic cholangiocarcinoma of the left liver, common bile duct carcinoma, and remnant cystic duct carcinoma. They were successfully removed via left hepatectomy combined with pylorus-preserving pancreatoduodenectomy. Furthermore, another intrahepatic cholangiocarcinoma developed 6 years after the second surgery, which was removed again via partial resection of the posterior segment of the liver. Histological findings of carcinomas represented various grades of cell differentiation. No predisposition toward carcinogenesis was found, since neither pancreaticobiliary maljunction nor primary sclerosing cholangitis was present, and the overexpression of cyclooxygenase-2 was negative in all resected specimens. Close monitoring for recurrence is warranted for early detection of metachronous carcinoma that might be effectively treated with repeated resection.

Biliopancreatic reflux-pathophysiology and clinical implications.

The common bile duct and the main pancreatic duct open into the duodenum, where they frequently form a common channel. The sphincter of Oddi is located at the distal end of the pancreatic and bile ducts; it regulates the outflow of bile and pancreatic juice. In patients with a pancreaticobiliary maljunction, the action of the sphincter does not functionally affect the junction. Therefore, in these patients, two-way regurgitation (pancreatobiliary and biliopancreatic reflux) occurs. This results in various pathological conditions of the biliary tract and the pancreas. Biliopancreatic reflux could be confirmed by: operative or postoperative T-tube cholangiography; CT combined with drip infusion cholangiography; histological detection of gallbladder cancer cells in the main pancreatic duct; and reflux of bile on the cut surface of the pancreas. Biliopancreatic reflux occurs frequently in patients with a long common channel. Although the true prevalence, degree, and pathophysiology of biliopancreatic reflux remain unclear, biliopancreatic reflux is related to the occurrence of acute pancreatitis. Obstruction of a long common channel easily causes bile flow into the pancreas. Even if no obstruction is present, biliopancreatic reflux can still result in acute pancreatitis in some cases.

Serum IgG4 levels and extrapancreatic lesions in autoimmune pancreatitis.

OBJECTIVE: Serum IgG4 levels are frequently elevated in patients with autoimmune pancreatitis (AIP). AIP is sometimes associated with various extrapancreatic lesions. This study examined whether there is a correlation between serum IgG4 levels and associated extrapancreatic lesions in AIP patients. METHODS: Serum IgG4 levels were measured in 40 AIP patients before therapy. In these patients, four associated extrapancreatic lesions (sclerosing cholangitis, sclerosing cholecystitis, sclerosing sialadenitis, and retroperitoneal fibrosis) and clinical factors, such as age, sex ratio, enlargement of the pancreas, and initial symptoms, were retrospectively assessed. RESULTS: The mean serum IgG4 level of the 40 AIP patients was 411+/-448 mg/dl. On the basis of the receiver operator characteristic curve data, the optimal cutoff value for the serum IgG4 to distinguish between AIP patients with and without extrapancreatic lesions was 220 mg/dl; 18 (78%) of 23 patients whose serum IgG4 was more than or equal to 220 mg/dl had extrapancreatic lesions, whereas four (24%) of 17 patients whose serum IgG4 was less than 220 mg/dl had extrapancreatic lesions (P=0.0011). No significant differences between the two groups in age, sex, the frequency of pancreatic enlargement or obstructive jaundice, and associated sialadenitis, retroperitoneal fibrosis, and diabetes mellitus were identified. Sclerosing cholangitis and cholecystitis were more frequent in patients with serum IgG4 levels of more than or equal to 220 mg/dl than in those with a lower serum IgG4 level (P=0.0002 and 0.0204, respectively). The number of associated extrapancreatic lesions was significantly greater in patients with a high-serum IgG4 level. CONCLUSION: AIP patients with serum IgG4 levels of more than or equal to 220 mg/dl frequently have extrapancreatic lesions.

Strategy for differentiating autoimmune pancreatitis from pancreatic cancer.

OBJECTIVES: It is of utmost importance that autoimmune pancreatitis (AIP) be differentiated from pancreatic cancer (PC) because some AIP cases undergo unnecessary laparotomy or pancreatic resection on suspicion of PC. This study aimed to develop an appropriate strategy for differentiating between AIP and PC. METHODS: Clinical, serological, and radiological features of 17 AIP patients forming a masslike lesion on pancreas head and 70 patients with pancreatic head cancer were compared. RESULTS: Numerous findings can be used to distinguish between AIP and PC, and the following are more likely in AIP: fluctuating jaundice; elevated serum IgG4 levels; delayed enhancement of the enlarged pancreas and a capsule-like low-density rim on computed tomography; long or skipped narrowed portion with side branches of the main pancreatic duct without upstream dilatation on endoscopic retrograde pancreatography, extrapancreatic lesions, such as stenosis of the intrahepatic bile duct, salivary gland swelling, and retroperitoneal mass; and responsiveness to steroid therapy. CONCLUSIONS: In elderly male patients presenting with obstructive jaundice and a pancreatic mass, AIP should be considered in the differential diagnosis. Based on a combination of clinical, serological, and radiological findings, AIP can be differentiated from PC. An algorithm for management of patients with a masslike lesion on pancreas head is presented.

Carcinoma arising in congenital choledochal cysts.

BACKGROUND/AIMS: Congenital choledochal cyst is almost always associated with pancreaticobiliary maljunction and is sometimes associated with biliary carcinoma. This study aimed to investigate the clinicopathological features and surgical treatment of choledochal cyst associated with carcinoma arising in the cyst wall. METHODOLOGY: Relationship of the clinicopathological findings and surgical treatment of 8 patients with histologically proven carcinoma that had developed in the choledochal cyst wall were examined to determine mode of tumor spread, multicentric tumor origins, and coincidence with other neoplastic lesions. RESULTS: Papillary adenocarcinoma (n = 5) had different clinicopathological features than tubular adenocarcinoma (n = 3). Radiologically, papillary adenocarcinoma presented as an eccentrically located polypoid mass in the cyst, while with tubular adenocarcinoma, there was evidence of bile duct stenosis with irregular thickening of the bile duct wall. Papillary adenocarcinoma was associated with extensive superficial spread (n = 1), synchronous (n = 2), or metachronous (n = 2) multicentric tumors. Pancreatoduodenectomy with (n = 1) or without (n = 1) hepatic lobectomy, and repeated resection by hepatic lobectomy (n = 2) were performed for these circumstances of tumors. Extensive or repeated resections allowed 3 patients to live longer than 2 years. Tubular adenocarcinoma was associated with scirrhously infiltrative spread and a poor prognosis. CONCLUSIONS: Papillary adenocarcinoma frequently occurs in the choledochal cyst wall. Since aggressive resection offers survival benefits in papillary adenocarcinoma arising in the choledochal cyst wall, the presence of superficial spread and multicentric tumors should be identified and taken into account when planning surgery. Patients require close monitoring so that recurrent carcinoma of the remnant bile duct can be identified early.

IgG4-related sclerosing disease.

Based on histological and immunohistochemical examination of various organs of patients with autoimmune pancreatitis (AIP), a novel clinicopathological entity of IgG4-related sclerosing disease has been proposed. This is a systemic disease that is characterized by extensive IgG4-positive plasma cells and T-lymphocyte infiltration of various organs. Clinical manifestations are apparent in the pancreas, bile duct, gallbladder, salivary gland, retroperitoneum, kidney, lung, and prostate, in which tissue fibrosis with obliterative phlebitis is pathologically induced. AIP is not simply pancreatitis but, in fact, is a pancreatic disease indicative of IgG4-related sclerosing diseases. This disease includes AIP, sclerosing cholangitis, cholecystitis, sialadenitis, retroperitoneal fibrosis, tubulointerstitial nephritis, interstitial pneumonia, prostatitis, inflammatory pseudotumor and lymphadenopathy, all IgG4-related. Most IgG4-related sclerosing diseases have been found to be associated with AIP, but also those without pancreatic involvement have been reported. In some cases, only one or two organs are clinically involved, while in others, three or four organs are affected. The disease occurs predominantly in older men and responds well to steroid therapy. Serum IgG4 levels and immunostaining with anti-IgG4 antibody are useful in making the diagnosis. Since malignant tumors are frequently suspected on initial presentation, IgG4-related sclerosing disease should be considered in the differential diagnosis to avoid unnecessary surgery.

A new diagnostic endoscopic tool for autoimmune pancreatitis.

BACKGROUND: Autoimmune pancreatitis (AIP) is a type of pancreatitis that is presumed to have an autoimmune etiology, and is currently diagnosed based on a combination of clinical, laboratory, and imaging studies. Although it is of utmost importance that AIP be differentiated from pancreatic cancer, AIP is sometimes difficult to differentiate from locally advanced pancreatic cancer. OBJECTIVE: To find a useful new method to diagnose AIP. DESIGN: Prospective study from June 2004 to September 2007. SETTING: Single public hospital. PATIENTS: Ten AIP patients, 10 patients with pancreatic cancer, and 10 patients with papillitis. INTERVENTIONS: Immunoglobulin (Ig)G4-immunostaining of biopsy specimens obtained from the major duodenal papilla. MAIN OUTCOME MEASUREMENTS: Number of immunohistochemically identified cells per high-power field (HPF) in each specimen were counted. RESULTS: Significant infiltration of IgG4-positive plasma cells (> or = 10/HPF) was observed in the major duodenal papilla of all 8 AIP patients with pancreatic head involvement. Moderate infiltration of IgG4-positive plasma cells (4-9/HPF) was detected in 1 patient with pancreatic head cancer, but there were rare (< or = 3/HPF) IgG4-positive plasma cells infiltrating the major duodenal papilla in 2 AIP patients who only had pancreatic body and/or tail involvement, 9 patients with pancreatic cancer, and 10 patients with papillitis. In the 3 AIP patients in whom biopsy specimens were retaken after steroid therapy, the number of IgG4-positive plasma cells decreased from significant to moderate in 2 patients and to < or = 3/HPF in 1 patient. LIMITATIONS: Small sample size. Endoscopists were not blinded to clinical information. CONCLUSIONS: IgG4 immunostaining of biopsy specimens obtained from the major duodenal papilla may be useful for supporting a diagnosis of AIP with pancreatic head involvement.

Sex-based differences in gallbladder cancer associated with pancreaticobiliary maljunction.

BACKGROUND/AIMS: Gallbladder cancer predominantly affects women; this sex-based difference is influenced by factors such as gallstones, sex hormone and genetic susceptibility. Gallbladder cancer is also frequently associated with pancreaticobiliary maljunction (PBM) without biliary dilatation. We examined sex-based differences in gallbladder cancer associated with PBM. METHODOLOGY: With a particular focus on gender differences, we retrospectively compared clinicopathological findings between 44 patients (9 men, 35 women) with PBM without biliary dilatation and 232 patients (60 men, 172 women) with gallbladder cancer that was not associated with PBM. RESULTS: Gallbladder cancer was detected in 75% of patients with PBM without biliary dilatation. Among PBM patients, gallbladder cancer was significantly more common in women than in men [29/35 (83%) us. 4/9 (44%), p<0.05]. Both men and women with gallbladder cancer associated with PBM were significantly younger at the time of diagnosis than patients with gallbladder cancer without PBM (p<0.01). Gallstones were detected in only 10% of women with gallbladder cancer with PBM, while gallstones were detected in 63% of women with gallbladder cancer without PBM (p<0.01). CONCLUSIONS: Gallbladder cancer occurs very frequently in patients with PBM without biliary dilatation, and women appear to be at a significantly higher risk than men.

Pancreas divisum in pancreaticobiliary maljunction.

BACKGROUND/AIMS: Pancreaticobiliary maljunction (PBM) and pancreas divisum (PD) are congenital anomalies that develop in the embryo at an early stage. They are possibly the result of bile and pancreatic duct misarrangement. We investigated the configuration of the pancreatic duct in patients with PBM and its clinical implications. METHODOLOGY: In 84 PBM patients, the configuration of the pancreatic duct and the presence of biliary cancer were documented. Patency of Santorini's duct was determined fluoroscopically or by dye-injection endoscopic retrograde pancreatography. Bile amylase levels were measured in 10 patients. RESULTS: Incomplete PD was detected in 8 (9.5%) of the 84 PBM patients. All of the 8 patients had a patent Santorini's duct, and only 1 patient had gallbladder cancer. The frequency of associated gallbladder cancer and the bile amylase level were significantly lower in PBM patients with a patent Santorini's duct than in PBM patients with a nonpatent Santorini's duct. CONCLUSIONS: PBM is sometimes associated with incomplete PD. In PBM patients with an incomplete PD, the incidence of cancer of the biliary tract may be lower, since pancreatic juice reflux into the bile duct might be reduced by the flow of pancreatic juice into the duodenum through Santorini's duct.

Appropriate steroid therapy for autoimmune pancreatitis based on long-term outcome.

OBJECTIVE: Because autoimmune pancreatitis (AIP) responds well to corticosteroids, many AIP patients are given this treatment. However, there is no consensus on the indications, dose, or duration of steroid treatment. The aim of this study was to establish the most appropriate steroid therapy regimen. MATERIAL AND METHODS: We retrospectively reviewed morphological and serological improvement after steroid therapy and long-term outcome including relapse in 41 AIP patients who were given steroid therapy and were prospectively followed-up for more than 1 year. RESULTS: All patients responded to steroid therapy, which was given because of bile duct stenosis secondary to sclerosing cholangitis in 34 AIP patients. Pancreatic enlargement normalized within one month; however, 13 patients had incomplete resolution of pancreatic duct narrowing, and 14 patients had incomplete resolution of bile duct stenosis. There was no correlation between the degree of morphological improvement and the initial prednisolone dose (30 mg and 40 mg/day). In 58% of 19 patients, serum IgG4 elevation failed to normalize. Glucose intolerance improved in 38% of the 21 patients with diabetes mellitus. Nine patients who had complete morphological and serological resolution, stopped their medication, and none have relapsed. Thirty-two patients continued maintenance therapy, and 4 of these patients suffered relapse. CONCLUSIONS: The indications for steroid therapy in AIP patients include bile duct stenosis caused by sclerosing cholangitis and other systemic diseases, such as retroperitoneal fibrosis and diabetes mellitus. We recommend that oral prednisolone be used at an initial dose of 30 mg/day; maintenance therapy is required in cases without complete morphological and serological resolution.

Efficacy of novel hypoxic cell sensitiser doranidazole in the treatment of locally advanced pancreatic cancer: long-term results of a placebo-controlled randomised study.

Novel hypoxic cell radiosensitiser doranidazole was tested for unresectable pancreatic cancer administered at intraoperative radiotherapy. Short-term survival was not different. However, difference has been observed concerning 3-year survival (doranidazole group vs. placebo; 23% vs. 0%, p=0.0192). This sensitiser might be effective in improving long-term survival for pancreatic cancer.

Pancreatographic investigation of pancreatic duct system and pancreaticobiliary malformation.

To clarify the anatomy of the pancreatic duct system and to investigate its embryology, we reviewed 256 pancreatograms with normal pancreatic head, 81 with pancreas divisum and 74 with pancreaticobiliary maljunction. Accessory pancreatograms were divided into two patterns. The long-type accessory pancreatic duct forms a straight line and joins the main pancreatic duct at the neck portion of the pancreas. The short-type accessory pancreatic duct joins the main pancreatic duct near its first inferior branch. The short-type accessory pancreatic duct is less likely to have a long inferior branch arising from the accessory pancreatic duct. The length of the accessory pancreatic duct from the orifice to the first long inferior branch was similar in the short- and long-type accessory pancreatic ducts. The first long inferior branch from the long-type accessory pancreatic duct passes though the main pancreatic duct near the origin of the inferior branch from the main pancreatic duct. Immunohistochemically, in the short-type accessory pancreatic duct, the main pancreatic duct between the junction with the short-type accessory pancreatic duct and the neck portion was located in the ventral pancreas. The long-type accessory pancreatic duct represents a continuation of the main duct of the dorsal pancreatic bud. The short-type accessory pancreatic duct is probably formed by the proximal main duct of the dorsal pancreatic bud and its long inferior branch.

Rectal cancer metastasis to the head of the pancreas treated with pancreaticoduodenectomy.

We report a case of a 50-year-old man who developed metastatic pancreatic cancer from a primary rectal cancer that had been curatively removed 3 years previously. The patient presented with a tumor that occupied the head of the pancreas, associated with obstructive jaundice, but the main pancreatic duct was not dilated. The patient was initially diagnosed as having primary pancreatic cancer. Cytological examination of the bile was conclusive for the presence of adenocarcinoma. The patient refused surgical treatment and chose to have gemcitabine therapy (1000 mg/body), which was given 27 times over 10 months. For 1 year, local disease progression was slow and no distant metastases developed; therefore, the initial diagnosis of pancreatic cancer was questioned. At that time, the patient asked for the tumor to be removed, and pancreaticoduodenectomy was performed. On histology, including immunohistochemical staining for cytokeratin 20 (positive) and cytokeratin 7 (negative), the tumor was shown to be a metastatic pancreatic carcinoma that had originated from the original rectal cancer.

The incidence of pancreatic and extrapancreatic cancers in Japanese patients with chronic pancreatitis.

BACKGROUND/AIMS: Although an association between chronic pancreatitis and malignancies has been reported in the Western literature, in Japan there have been few reports that have dealt with this issue. We investigated the incidence of pancreatic and extrapancreatic cancers in Japanese patients with chronic pancreatitis. METHODOLOGY: We studied 170 Japanese patients with definite chronic pancreatitis with respect to the occurrence of pancreatic and extrapancreatic cancers during follow-up and compared the incidence with that reported in the Western literature. RESULTS: The patients developed 29 cancers including 5 pancreatic cancers. Four patients had two different types of cancer. The extrapancreatic cancer incidence (24/170: 14.1%) was significantly higher than in the West (8.3%, p < 0.01). The major organs in which cancer developed were stomach (n=9), pancreas (n=5), esophagus (n=4), colon (n=3), lung (n=2) and hemopoietic tissue (n=2). The overall incidence (8.2%) of associated cancers of the digestive system including, stomach, intestine, liver, biliary duct, and gallbladder, was significantly higher than in the West (1.3%, p < 0.01). CONCLUSIONS: The risk of extrapancreatic cancers during the course of chronic pancreatitis is significantly increased in Japan than in Western countries. In particular, cancers of the digestive system are frequently associated with chronic pancreatitis in Japan.

Tumor size significantly correlates with postoperative liver metastases and COX-2 expression in patients with resectable pancreatic cancer.

BACKGROUND/AIM: Local treatment often fails in patients with resectable pancreatic cancer due to the postoperative development of distant metastases, especially liver metastases. We determined the prognostic factors for postoperative liver metastases in pancreatic cancer patients following surgical resection with combined radiotherapy. METHODS: Sixty-four patients with nonmetastatic, resectable pancreatic cancer were entered into this study. All of these patients had pancreatic resection surgery combined with radiotherapy. The development of postoperative liver metastases was carefully followed, and the survival ratio was evaluated using the Kaplan-Meier method. The prognostic importance of clinicopathological factors and molecular characteristics was analyzed by the Cox proportional hazards model. The correlation study was performed using Fisher's exact test. RESULTS: Tumor size, curability, and histological type of differentiation were statistically significant independent prognostic factors. On multivariate analysis, curability and histological type of differentiation were statistically significant. Only tumor size (> or = 3 cm) was significantly correlated with postoperative liver metastases, as well as cyclooxygenase-2 expression. CONCLUSIONS: There were three significant prognostic factors in patients with resectable pancreatic cancer who had local therapy. Patients who have a large tumor require particularly careful follow-up for postoperative liver metastases.

Prognosis of autoimmune pancreatitis.

Autoimmune pancreatitis (AIP) is responsive to steroid therapy, but some AIP patients improve spontaneously, or only improve after biliary drainage. Pancreatic enlargement and irregular narrowing of the main pancreatic duct usually improves in almost all patients, but marked atrophy of the pancreas develops in some patients. Biliary stenosis improves to various degrees, and a biliary drainage tube can be withdrawn. Other extrapancreatic lesions, including swelling of the salivary or lacrimal glands, lymphadenopathy, and retroperitoneal fibrosis also improve with steroid therapy. Pancreatic endocrine and exocrine function is frequently impaired in AIP patients, and steroid therapy is occasionally effective for these dysfunction. Deterioration of pancreatic exocrine function is rarely detected after steroid therapy. In the literature, the recurrence rate of AIP was reported to be about 17% (range 6% to 26%). AIP patients who relapse during maintenance steroid therapy or after stopping steroid medication should be re-treated with a high-dose steroid. Although AIP is rarely associated with pancreatic stones, stones are formed in some relapsing AIP patients. The long-term prognosis for AIP is unknown. As the pancreatic exocrine and endocrine functions as well as the morphological findings are reversible after steroid therapy, the prognosis for AIP seems better than that of chronic pancreatitis, which is usually followed by exocrine and endocrine pancreatic insufficiency with disease progression. Although carcinogenesis of AIP is unknown, some AIP patients developed a malignancy during follow-up. Since AIP occurs predominantly in the elderly, clinicians should pay attention to any complicating diseases in follow-up of AIP patients. Further studies are necessary to clarify the pathogenesis as well as the long-term prognosis of AIP.

Pancreatographic investigation of embryology of complete and incomplete pancreas divisum.

OBJECTIVES: To investigate embryology of complete and incomplete pancreas divisum (PD). METHODS: We analyzed anatomy of the pancreatic duct system in 44 cases of complete PD and 41 cases of incomplete PD. Under the concept of branch fusion between the ventral and dorsal pancreatic ducts, incomplete PD was divided into 3 types: fusion of the extreme end of the upper branch of the ventral pancreatic duct with the dorsal pancreatic duct (type 1); fusion of the lower branch of the dorsal pancreatic duct with the lower branch of the ventral pancreatic duct (type 2); and fusion of the lower branch of the dorsal pancreatic duct with the ventral pancreatic duct (type 3). RESULTS: Complete PD showing no ventral pancreatic duct radiologically might be induced by complete regression of the ventral pancreatic duct near the orifice in the pancreas with communication between the ventral and dorsal pancreatic ducts. Embryological mechanism of incomplete PD (type 1, n = 16; type 2, n = 10; and type 3, n = 15) was confirmed by measurement in pancreatograms. CONCLUSIONS: Some cases of complete PD might be induced by complete regression of the ventral pancreatic duct near the orifice. Embryology of incomplete PD can be accounted by concept of branch fusion.