Autoimmune pancreatitis: CT and MR characteristics

Usefulness of endoscopic observation of the main duodenal papilla in the diagnosis of sclerosing pancreatitis

BACKGROUND

There are no descriptions of the appearance of the main duodenal papilla in sclerosing pancreatitis. The intent of the present study was to clarify the characteristics of the main duodenal papilla in patients with sclerosing pancreatitis.

METHODS

Macroscopic findings at ERCP with reference to the main duodenal papilla of 17 patients with sclerosing pancreatitis were compared with those of 24 patients with normal ERCP findings, 11 with chronic pancreatitis, 13 with primary sclerosing cholangitis, 21 with pancreatic cancer, and 18 with bile duct cancer. Endoscopic photographs of the papilla were reviewed retrospectively by 3 observers blinded to the underlying pancreaticobiliary pathology. Degree of swelling was scored in all patients. Biopsy specimens from swollen papillae were assessed histopathologically in 3 patients with sclerosing pancreatitis.

RESULTS

Severe swelling of the main duodenal papilla was observed in 7 (41%) of 17 patients with sclerosing pancreatitis. The total score for the degree of swelling in patients with sclerosing pancreatitis was significantly higher than that for patients with a normal ERCP, chronic pancreatitis, primary sclerosing cholangitis, pancreatic cancer, and bile duct cancer (p < 0.01). T-lymphocyte infiltration of the papilla was evident in the biopsies from 3 patients with sclerosing pancreatitis.

CONCLUSIONS

A swollen main duodenal papilla was a characteristic finding in patients with sclerosing pancreatitis. T-lymphocyte infiltration is present in the swollen main duodenal papilla. These features may be useful in the diagnosis of sclerosing pancreatitis.

Do patients with primary sclerosing cholangitis have a greater frequency of pancreatic abnormalities at MRI than patients with other liver diseases?

PURPOSE

It has been proposed that there is an increased frequency of pancreatic abnormalities in patients with primary sclerosing cholangitis (PSC). Our purpose is to compare the frequency of pancreatic abnormalities detected at MRI in patients with PSC and to compare these findings with those found in a matched cohort with other liver diseases.

METHOD

We identified 29 patients who had either a histologic or an endoscopic retrograde cholangiopancreatography diagnosis of PSC and 29 age- and gender-matched patients with liver disease without PSC who underwent MRI at 1.5 T. The protocol included breath-hold T1-weighted gradient echo, echo train, fast spin echo, T2-weighted images and dynamic gadolinium-enhanced MRI. Two blinded readers retrospectively evaluated the MR images for abnormalities of pancreatic size and morphology, T1 and T2 signal intensity, duct size and irregularities, arterial-phase contrast enhancement, focal pancreatic masses, cystic lesions, peripancreatic fluid/edema, ascites, and capsular-like rim surrounding the pancreas.

RESULTS

The prevalence of pancreatic and peripancreatic abnormalities was 10 of 29 (35%) in PSC patients and 14 of 29 (48%) in control patients. MR findings included ascites (9 PSC, 12 controls), peripancreatic edema (7 PSC, 11 controls), atrophy (4 PSC, 3 control), increased T2 signal (3 PSC, 4 controls), cystic lesions (2 PSC, 3 controls), abnormal T1 signal (1 PSC, 2 controls), and dilated pancreatic ducts (3 PSC, 2 controls). Quantitative parameters were not significantly different between PSC patients and the control subjects with pancreatic findings.

CONCLUSION

There is no significant difference in pancreatic abnormalities detected on MRI between patients with PSC and those with other liver diseases.

Clinical study of chronic pancreatitis with focal irregular narrowing of the main pancreatic duct and mass formation: comparison with chronic pancreatitis showing diffuse irregular narrowing of the main pancreatic duct

INTRODUCTION

Main pancreatic duct (MPD)-narrowed chronic pancreatitis (CP) may be an autoimmune abnormality. It also has been called autoimmune pancreatitis and sclerosing pancreatitis. It is unclear whether cases with focal pancreatographic changes are part of the same clinical entity as cases with diffuse MPD changes.

AIM AND METHODOLOGY

We reviewed seven cases of chronic pancreatitis (CP) with focal narrowing of the main pancreatic duct (MPD), evidenced by endoscopic retrograde cholangiopancreatography (ERCP), and swelling of one or two segments of the pancreas, evidenced by ultrasonography (US) /computed tomography (CT), and indicated the clinicopathologic features of focal-type MPD-narrowed CP.

RESULTS

The patient group comprised six men and one woman, and their age range was 28-75 years, with a mean of 63.7 years. Affected sites were in the head in two patients, the body in one patient, the tail in one patient, and the body and tail in three patients; ERP showed narrowing in six patients and obstruction in one. Stricture of the lower portion of the common bile duct (CBD) that caused obstructive jaundice was shown by ERC in two cases in which the pancreas head was affected. In all six patients, a dynamic study by CT or MRI homogeneously showed delayed enhancement of involved segments of the pancreas. Serum levels of pancreatic enzyme were elevated in five patients, but only one subject had pancreatitis-like epigastric pain. Serological evidence suggestive of autoimmune abnormality was detected in only three patients with hypergammaglobulinemia (> or =2.0 g/dL) or positive titers of antinuclear antibody (ANA; > or =80). Histological assessment was available for five patients, who characteristically had dense lymphocytic or plasmocytic infiltration with severe fibrosis that caused luminal narrowing. The clinical, serologic, and histologic findings as described above were comparable to those for 12 CP patients with diffuse narrowing of the MPD, diagnosed during the same period. Surgical resection was performed in 5 patients, in 2 of whom a similar inflammatory process recurred in the remnant head of the pancreas, whereas pancreatitis no longer developed in the other 3 patients. One patient was initially treated with steroids, with clinical remission, although there was neither hypergammaglobulinemia nor positive ANA.

CONCLUSION

These results indicate that CP with focal narrowing of the MPD is part of the same clinical spectrum as CP with diffuse narrowing of the MPD, and whether the distribution is diffuse or focal seems to be related to the stage or the extent of the disease. It is therefore important to recognize the possible existence of this focal variant to avoid unnecessary surgery.

Current status of imaging in pancreatic diseases

Recent technological developments in multidetector CT allow pancreatic imaging in a single breath-hold, which is especially valuable in obtaining isotropic three-dimensional reformations that improve our ability to provide accurate preoperative vascular mapping. Advanced MR technology allows faster imaging of pancreas, thus facilitating MR cholangiopancreatography. Use of tissue-specific MR contrast agents, endoscopic ultrasound, and positron emission tomography (PET) in pancreatic imaging has evolved considerably. This review article discusses the roles of CT, MR, endoscopic ultrasound, and PET imaging in the pancreas.

Autoimmune pancreatitis: possibilities of CT characterization

BACKGROUND

Pancreatitis is defined as an inflammatory disease of the pancreas, leading to morphological and pathological changes. Recently, an autoimmune pathogenesis of this disease has been proposed. This type of pancreatitis should be differentiated from other pancreatic diseases, since appropriate therapy is effective and morphological changes and pancreatic function can recover to normal levels.

AIM OF THE STUDY

To assess the possibility of distinguishing autoimmune pancreatitis from other pancreatic diseases with an analogous clinical presentation on the basis of CT findings alone.

METHODS

The CT images of 7 patients with proven autoimmune pancreatitis, along with those of 20 patients with other pancreatic diseases, but with an analogous clinical presentation, were retrospectively evaluated in a blinded fashion by 2 radiologists. In particular, the radiologists had to search for the typical signs of autoimmune pancreatitis. Discordant cases were further analyzed in the presence of a 3rd radiologist. The final diagnosis was acquired by means of a majority or overall consensus. The sensitivity, specificity, positive and negative predictive values of CT were calculated against each of the diseases (autoimmune pancreatitis; other pancreatic diseases), in order to evaluate the diagnostic value of the scan.

RESULTS

After the consensus evaluation, the correct diagnosis was reached in 25/27 (92.5%) cases, with only 2/27 wrong diagnoses (autoimmune pancreatitis diagnosed as another pancreatic disease and vice versa). The sensitivity and specificity of CT against autoimmune pancreatitis were 86 and 95%, respectively. The positive and negative predictive values were 89 and 93%, respectively.

CONCLUSION

Patients with autoimmune pancreatitis demonstrate imaging findings that enable the correct diagnosis by dynamic CT, even in the presence of nonspecific clinical symptoms. The precise classification of the disease is extremely important, since simple steroid therapy then represents the correct treatment, and leads to complete recovery.

Bile duct involvement in a case of autoimmune pancreatitis successfully treated with an oral steroid

In the case reported here, the characteristic features of AIP were evaluated by ultrasonography, computed tomography and endoscopic retrograde cholangiopancreatography, initially in the intrahepatic- and extrahepatic bile ducts, and later in the pancreas. In addition, histological examination revealed lymphocytic sclerosis around the intralobular bile ducts, as is reported in AIP, without chronic nonsuppurative destructive cholangitis or onion-skin-like appearance. Immunohistochemistry identified the infiltrating lymphocytes as T cells. Although hypergammaglobulinemia was observed with elevation of hepatobiliary and pancreatic enzymes, no other serological or physiological abnormalities suggestive of other systemic autoimmune diseases were detected. These findings progressed over a three-month period and were dramatically resolved within one month by steroid therapy. These observations support a novel clinical entity characterized by the presence of bile duct lesions similar to the pancreatic involvement seen in AIP that is distinct pathophysiologically, histologically, and therapeutically from the so-called autoimmune cholangitis or primary sclerosing cholangitis.

Clinical relevance of autoimmune-related pancreatitis

Recently, a concept of 'autoimmune pancreatitis' (AIP) was proposed. Computed tomography, magnetic resonance imaging or ultrasonography show a diffusely enlarged pancreas with a so-called 'sausage-like' appearance. Hypergammaglobulinaemia, increased serum levels of total IgG or IgG4, positive autoantibodies such as antinuclear antibody, anti-lactoferrin antibody, anti-CA-II antibody, rheumatoid factor and anti-smooth muscle antibody, were often observed in patients with AIP. Microscopic findings showed fibrotic changes with infiltration of lymphocytes, plasmacytes and sometimes eosinophils in the pancreas. Major subgroups of lymphocytes infiltrating areas around pancreatic ducts were CD4(+) T-cells producing IFN-gamma. HLA-DR was expressed on pancreatic duct cells as well as CD4(+) cells. The diagnosis is made by a combination of clinical, laboratory and morphological findings. Laboratory data, pancreas images and diabetes mellitus in most patients do respond to steroid treatment. In conclusion, autoimmune-related pancreatitis appears to be a unique clinical entity. However, its importance in clinical practice needs further characterization.

Autoimmune pancreatitis

The recommended treatment for a focal mass in the head of the pancreas is pancreaticoduodenectomy. Preoperative biopsy is not advised in patients who are candidates for resection because of the documented risk of tumour dissemination along the needle tract and significant false negative results.1 Autoimmune pancreatitis is a relatively uncommon condition that can present as a pancreatic mass and mimic malignancy. It may respond to glucocorticoid therapy, and further assessment of such treatment is indicated.2 Such experience will only accumulate if wider knowledge of this condition leads to clinical suspicion.

ERCP features in 27 patients with autoimmune pancreatitis

BACKGROUND

Autoimmune pancreatitis has been proposed as a new clinical entity. However, the ERCP features of this entity have not been well described.

METHODS

Clinical and radiographic features in 27 patients with a diagnosis of autoimmune pancreatitis were evaluated.

RESULTS

All 27 patients were at first suspected to have pancreatic cancer. The patients were predominantly elderly men and presented with jaundice or mild symptoms and pancreatic enlargement, but no attack of acute pancreatitis. A cholestatic biochemical profile and serum IgG elevation were usually present. A diffusely or segmentally irregular and narrow main pancreatic duct and a positive response to corticosteroid therapy were characteristic. During observation without treatment, serial pancreatography in 2 patients demonstrated progression of diffuse, irregular narrowing of the main pancreatic duct over periods, respectively, of 2 and 6 months. Both the irregular narrowing of the main pancreatic duct and distal bile duct strictures improved in various degrees in response to corticosteroid therapy.

CONCLUSIONS

Segmental or diffuse irregular narrowing of the main pancreatic duct are ERCP features of autoimmune pancreatitis.

Autoimmune-related Pancreatitis

The treatment of patients with autoimmune pancreatitis poses a challenge to the clinician. Prednisone, in an initial dosage of 30 to 40 mg/d, is used in patients with moderate abdominal and back pain, obstructive jaundice, or sclerosing cholangitis. Antacid or anticholinergic agents may be used to minimize stimulation of pancreatic exocrine function. Patients with quiescent disease may not need pharmacologic medication. In patients with complications such as obstructive jaundice and infection, biliary drainage and administration of antibiotics are recommended prior to steroid therapy. Steroid therapy occasionally ameliorates diabetes mellitus associated with autoimmune pancreatitis.

MR imaging of pancreatic diseases

This article presents current MR imaging techniques for the pancreas, and review a spectrum of MR imaging features of various pancreatic diseases. These include: 1) congenital anomalies such as anomalous union of pancreatobiliary ducts, divisum, and annular pancreas, 2) inflammatory diseases, including acute or chronic pancreatitis with complications, groove pancreatitis, and autoimmune pancreatitis, tumor-forming pancreatitis, 3) pancreatic neoplasms, including adenocarcinoma, islet cell tumors, and cystic neoplasms (microcystic adenoma, mucinous cystic neoplasms, and intraductal mucin-producing pancreatic tumor). Particular attention is paid to technical advances in MR imaging of the pancreas such as fat-suppression, MR pancreatography (single- or multi-slice HASTE), and thin-section 3D multiphasic contrast-enhanced dynamic sequences. Imaging characteristics that may lead to a specific diagnosis or narrow the differential diagnosis are also discussed.

Chronic pancreatitis: diagnosis, classification, and new genetic developments

The utilization of recent advances in molecular and genomic technologies and progress in pancreatic imaging techniques provided remarkable insight into genetic, environmental, immunologic, and pathobiological factors leading to chronic pancreatitis. Translation of these advances into clinical practice demands a reassessment of current approaches to diagnosis, classification, and staging. We conclude that an adequate pancreatic biopsy must be the gold standard against which all diagnostic approaches are judged. Although computed tomography remains the initial test of choice for the diagnosis of chronic pancreatitis, the roles of endoscopic retrograde pancreatography, endoscopic ultrasonography, and magnetic resonance imaging are considered. Once chronic pancreatitis is diagnosed, proper classification becomes important. Major predisposing risk factors to chronic pancreatitis may be categorized as either (1) toxic-metabolic, (2) idiopathic, (3) genetic, (4) autoimmune, (5) recurrent and severe acute pancreatitis, or (6) obstructive (TIGAR-O system). After classification, staging of pancreatic function, injury, and fibrosis becomes the next major concern. Further research is needed to determine the clinical and natural history of chronic pancreatitis developing in the context of various risk factors. New methods are needed for early diagnosis of chronic pancreatitis, and new therapies are needed to determine whether interventions will delay or prevent the progression of the irreversible damage characterizing end-stage chronic pancreatitis.

Autoimmune pancreatitis detected as a mass in the tail of the pancreas

A mass in the tail of the pancreas was detected in a 62-year-old male patient who had hypergammaglobulinaemia, and was positive for antinuclear antigen and anti-SS-A antibody. Endoscopic retrograde pancreatography revealed focal irregular narrowing of the main pancreatic duct in the tail of the pancreas. Dynamic computed tomography showed swelling of the pancreatic tail, which was enhanced on delayed phase. Autoimmune pancreatitis was suspected and corticosteroid therapy was commenced. This led to significant resolution of the pancreatic stricture. It is important to recognize this clinical entity as corticosteroid therapy may avoid unnecessary surgery.