Autoimmune pancreatitis

Autoimmune pancreatitis and non-necrotizing acute pancreatitis: computed tomography pattern

OBJECTIVES

To retrospectively differentiate diffuse autoimmune pancreatitis from non-necrotizing acute pancreatitis at clinical onset with multi detector row computed tomography.

METHODS

36 Patients suffering from diffuse autoimmune pancreatitis (14) or non-necrotizing acute pancreatitis (22) were enrolled. Qualitative analysis included stranding, retroperitoneal fluid film, capsule-like rim enhancement and pleural effusion. In quantitative analysis pancreatic density was measured in all phases. The vascularization behaviour was assessed using the relative enhancement rate across all phases.

RESULTS

Pancreatic density resulted lower in non-necrotizing acute pancreatitis compared to diffuse autoimmune pancreatitis patients in pre-contrast phase and higher in pancreatic phase. Relative enhancement rate evaluation confirmed different vascularization behaviours of the two diseases. Only non-necrotizing acute pancreatitis Patients presented peripancreatic stranding and fluid in the retromesenteric interfascial plane.

CONCLUSIONS

Multi detector row computed tomography is a useful technique for differentiating diffuse autoimmune pancreatitis from non-necrotizing acute pancreatitis at clinical onset. Peripancreatic stranding and retroperitoneal fluid film, characteristic of non-necrotizing acute pancreatitis, and late-phase peripheral rim enhancement, characteristic of diffuse autoimmune pancreatitis, provide qualitative clues to the differentiation. A quantitative study of contrast enhancement patterns, considering the relative enhancement rate, can assist in the differential diagnoses of two diseases.

Lymphoplasmacytic sclerosing pancreatitis (autoimmune pancreatitis): evaluation with multidetector CT

Lymphoplasmacytic sclerosing pancreatitis is a form of chronic pancreatitis characterized by a mixed inflammatory infiltrate that centers on the pancreatic ducts. It is a cause of benign pancreatic disease that can clinically mimic pancreatic cancer. Preoperative detection of lymphoplasmacytic sclerosing pancreatitis is important because patients usually respond to steroid therapy. Patients with lymphoplasmacytic sclerosing pancreatitis are often referred for computed tomography (CT) when they are suspected of having a pancreatic or biliary neoplasm; therefore, it is important to search for potential findings suggestive of lymphoplasmacytic sclerosing pancreatitis when typical findings of a pancreatic or biliary neoplasm are not found. Typical CT findings include diffuse or focal enlargement of the pancreas without dilatation of the main pancreatic duct. Focal enlargement is most commonly seen in the head of the pancreas, and the involved pancreas on contrast material-enhanced CT images may be iso-attenuating relative to the rest of the pancreas, or hypo-attenuating, especially during the early postcontrast phase. Thickening and contrast enhancement of the wall of the common bile duct and gallbladder may reflect inflammatory infiltrate and fibrosis associated with lymphoplasmacytic sclerosing pancreatitis. There are several features seen at CT that may help to differentiate lymphoplasmacytic sclerosing pancreatitis from pancreatic cancer, such as diffuse enlargement of the pancreas with minimal peripancreatic stranding in patients with obstructive jaundice, an absence of significant pancreatic atrophy, and an absence of significant main pancreatic duct dilatation. When these findings are encountered, clinical, other imaging, and serologic data should be evaluated.

Autoimmune pancreatitis in young patients

GOALS

To examine whether there is a difference in the autoimmune pancreatitis (AIP) seen in young and elderly patients.

BACKGROUND

AIP has a preponderance for elderly males, although the reason is unknown.

STUDY

A total of 64 patients with AIP were divided into a young (<40 y old) group and a middle-aged or elderly group (> or =40 y old) according to the age at diagnosis. The clinical findings of each group were compared.

RESULTS

The young group consisted of 6 patients (3 men, 3 women) with a mean age of 33.0 (range, 28 to 37) years. In the middle-aged or elderly group, there were 58 patients with a mean age of 66.4 (range, 46 to 83) years; males predominated (79%). Abdominal pain as the presenting symptom was significantly more frequent in the young group than in the middle-aged or elderly group (100% vs. 43%, P<0.05). Obstructive jaundice was detected in only 17% (1/6) of patients in the young group compared with 59% (34/58) of patients in the middle-aged or elderly group. Serum amylase elevations were detected more frequently in the young group than in the middle-aged or elderly group (83% vs. 40%, P<0.05). One young patient also had ulcerative colitis.

CONCLUSIONS

Although rare in Japan, young patients with AIP show different clinical features from middle-aged or elderly patients with AIP; young patients are more likely to have abdominal pain and serum amylase elevations.

Lymphoplasmacytic sclerosing pancreatitis with obstructive jaundice: CT and pathology features

OBJECTIVE

The clinical presentation of lymphoplasmacytic sclerosing pancreatitis (LPSP) can be very similar to that of pancreatic cancer, with no statistically significant differences in the rates of abdominal pain, weight loss, jaundice, or levels of carcinoembryonic agent or cancer antigen 19-9. The purpose of this study is to describe and illustrate the CT features of LPSP presenting with obstructive jaundice and to correlate CT and pathology findings.

MATERIALS AND METHODS

Five patients with LPSP were evaluated. Morphologic features of the pancreas on CT scans, including the size of the pancreas, presence or absence of a mass, segmental difference of contrast enhancement, pancreatic duct, major pancreatic vasculature, and biliary tract, were retrospectively evaluated and correlated with histopathology. The degree of contrast enhancement of the pancreas was compared in 10 patients without LPSP, who were scanned with the same protocol.

RESULTS

CT scans showed diffuse (n = 2) or focal (n = 3) enlargement of the pancreatic head. The normal lobular appearance of the pancreas was effaced, and the gland appeared featureless in the involved region. Enlarged areas showed an enhancement pattern similar to that of the rest of the pancreas, and no segmental difference of contrast enhancement was identified. Pancreatic duct dilatation was not seen in any patient. Thickening and contrast enhancement of the common bile duct wall (n = 4) and gallbladder wall (n = 3) were observed and were pathologically correlated with inflammatory infiltrate and fibrosis of the common bile duct (n = 3) and gallbladder (n = 1).

CONCLUSION

When these findings are encountered, further evaluation with serologic tests or biopsy may aid in the diagnosis of LPSP.