 Advertisement | ||||||||
 | ||||||||
|
||||||||
 |
 |
 |
 |
 |
 |
 |
||
|
| Case Report |
From the Departments of Surgery (Rudmik, Dixon), Internal Medicine (Nash, Kinnear), Pathology (Trpkov, Falck) and Urology (Dushinski), University of Calgary, Calgary, Alta.
Correspondence to: Elijah Dixon, University of Calgary, Tom Baker Cancer Centre, 1331 29th St. NW, Calgary AB T2N 4N2; fax 403 283-1651; elijah.dixon{at}calgaryhealthregion.ca
 |
Abstract |
|---|
 Top Abstract CommentsREFERENCES |
|---|
A CT scan of the abdomen showed a bulky and heterogeneous mass in the pancreatic head, neck and uncinate (Fig. 1A), with encasement of the superior mesenteric vein (Fig. 1B). Although multiple retroperitoneal lymph nodes were identified, none was enlarged enough to fulfill the size criteria for metastasis. Three solid lesions were noted in the left kidney, with the largest measuring 1.7 cm in diameter; 3 lesions were identified in the right kidney, with the largest measuring 1.5 cm. The contrast-enhanced scans demonstrated that the lesions did not represent hyperdense cysts (Fig. 1C). A subsequent MRI confirmed the CT findings.
|
An endoscopic ultrasound-guided fine-needle biopsy of the pancreatic mass was performed, and cytology of the aspirate revealed no malignant cells. However, we felt that the diagnosis of pancreatic cancer could not be completely ruled out, so we performed a percutaneous biopsy of the pancreatic lesion. Needle-core biopsies of the pancreas demonstrated morphology suggestive of autoimmune pancreatitis. The pancreatic tissue was almost completely replaced with fibrous tissue and an inflammatory infiltrate composed of lymphocytes and plasma cells, which were positive for IgG4 (Fig. 2A and B). A biopsy of the duodenum revealed duodenitis with loss of mucosal villi and extensive lymphoplasmacytic and eosinophilic infiltration, which stained positive for IgG4.
|
Laparoscopic resection was performed of one of the renal lesions, which proved to be non-neoplastic and revealed chronic tubulointerstitial nephritis with extensive interstitial fibrosis. As with the previous biopsies, there was diffuse inflammatory lymphoplasmacytic and eosinophilic infiltrate in the interstitium, which resulted in tubular obliteration (Fig. 3A and B). No microorganisms or viral inclusions were identified. On immunochemistry there was a mixture of T and B lymphocytes; plasma cells marked uniformly for IgG and IgG4 and showed no light-chain restriction. Subsequent laboratory studies revealed elevated serum IgG and IgG4 levels. Serum electrophoresis demonstrated a slightly elevated gamma globulin level, while rheumatoid factor and antinuclear antibody levels were normal. No fresh renal tissue was available for immunofluoresence to determine whether antitubular basement membrane antibodies were present.
|
We initiated a treatment regimen for a presumed diagnosis of autoimmune pancreatitis with prednisone (40 mg/d) for 4 weeks. A follow-up CT scan of the abdomen revealed a normal-sized pancreas with complete resolution of the swelling (Fig. 4A and B). The largest renal lesion decreased in size, and the remaining lesions were not identifiable on the repeat CT scan (Fig. 4C).
|
At 13 months' follow-up the patient was asymptomatic after having been off the steroid therapy for 5 months. However, a CT scan demonstrated a recurrence, since the pancreatic body was slightly enlarged and the renal lesions had increased in size. The patient was given azathioprine (75 mg once daily) for 6 months to induce and sustain a response.
Follow-up CT and MRI scans performed at 22 months demonstrated a normal-looking pancreas and stable renal lesions. The patient was free of disease, and results of all laboratory studies, including creatinine level, urinalysis results and levels of IgG and IgG4 and other autoimmune markers, were normal.
|
Comments |
|---|
|
TopAbstractCommentsREFERENCES |
|---|
Autoimmune pancreatitis is a chronic inflammatory disorder hypothesized to be induced from autoantibodies directed toward the pancreatic duct epithelium.3 It was first described in 1961 by Sarles and colleagues as a case of pancreatitis with hypergammaglobulinemia.4 Thirty-five years later, in 1996, Kino-Ohsaki and colleagues shed light onto its pathogenesis, demonstrating that carbonic anhydrase II, an enzyme located in pancreatic duct epithelium, is a target of the acquired autoantibodies.5 Recently, Hamano and colleagues6 reported that elevated concentrations of IgG4 were closely associated with autoimmune pancreatitis. Okazaki and colleagues7 demonstrated that anti-lactoferrin antibody, antinuclear antibody and rheumatoid factor may also be elevated. Kamisawa and colleagues were the first to postulate that autoimmune pancreatitis may be part of an IgG4-positive systemic autoimmune disease characterized by IgG4 plasma cell deposition in various organs, including the pancreas, the portal area of the liver, the lungs, the kidneys, gastric and colonic mucosa and bone marrow.8 Although the exact role of these antibodies has yet to be confirmed, the underlying inflammation produces pancreatic swelling, which is often misdiagnosed as pancreatic cancer. Since the management of autoimmune pancreatitis is medical, in contrast to the surgical treatment of adenocarcinoma, an accurate diagnosis is important to avoid an unnecessary pancreatic resection.
Although the exact incidence of autoimmune pancreatitis is unknown, a recent review reported the overall incidence to be from 1.9% to 6.6%.9 We know of only 1 case in North America that was diagnosed before surgery.10 The majority of the documented cases originate from Japan, Korea and Europe. Most cases in North America have been reported after pancreaticoduodenectomy because of a preoperative diagnosis of pancreatic cancer. Recently, 2 large patient series reported that 2.3% of pancreaticoduodenectomies revealed a misdiagnosed case of autoimmune pancreatitis.11,12
The diagnosis of autoimmune pancreatitis is difficult, since the clinical presentation and findings on abdominal imaging often mimic pancreatic cancer. Both disorders affect similar age groups (60–65 years) and show slight male predilection (64%–68%).11,12 The most common symptoms are also similar and include vague abdominal pain, weight loss, jaundice, night sweats, new-onset diabetes and steatorrhea. On radiographic imaging, a mass in the head of the pancreas is the most common finding in both disorders.
Despite the similar presentation, certain clinical features favour a diagnosis of autoimmune pancreatitis and warrant further investigation, in particular the presence of other autoimmune disorders such as primary sclerosing cholangitis, Sjögren's syndrome, diabetes mellitus and tubulointerstitial nephritis.13 A fluctuating course of jaundice was found in 33% of patients with autoimmune pancreatitis.14 Radiographically, diffuse glandular enlargement with delayed enhancement of the swollen pancreatic parenchyema is often identified, and endoscopic retrograde cholangiopancreatography often demonstrates segmental and diffuse narrowing of the main pancreatic duct.14,15
When autoimmune pancreatitis is suspected, tissue biopsy remains the "gold standard" for diagnosis. Histologically, the condition is characterized by dense periductal lymphoplasmacytic infiltration, periductal and parenchymal fibrosis and obliterative venulitis.16 Measurement of the serum IgG4 level should be considered when differentiating between autoimmune pancreatitis and pancreatic adenocarcinoma, since it has a 97% accuracy, 95% sensitivity and 97% specificity.6
Autoimmune pancreatitis responds well to corticosteroid treatment.13,17,18 Suggested indications for steroid therapy include obstructive jaundice and the presence of associated autoimmune disorders, such as diabetes mellitus.18 The recommended treatment regimen is a starting dose of 30–40 mg/d of prednisone until symptoms improve, followed by dose tapering of 5 mg/w.13,14 A follow-up CT scan can be performed to document pancreatic size reduction and to ensure that pancreatic cancer has not been misdiagnosed as autoimmune pancreatitis. If the symptoms recur, subsequent abdominal imaging and repeat tissue biopsy should clarify the diagnosis.
|
Footnotes |
|---|
Contributors: All of the authors contributed to the manuscript through data collection and manuscript development and have approved the final version to be published.
Competing interests: None declared.
|
REFERENCES |
|---|
|
TopAbstractCommentsREFERENCES |
|---|
This article has been cited by other articles:
|
|
 |
|
  N. Mise, Y. Tomizawa, A. Fujii, Y. Yamaguchi, and T. Sugimoto A case of tubulointerstitial nephritis in IgG4-related systemic disease with markedly enlarged kidneys NDT Plus, June 1, 2009; 2(3): 233 - 235. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 N. Takahashi, J. G. Fletcher, J. L. Fidler, D. M. Hough, A. Kawashima, and S. T. Chari Dual-Phase CT of Autoimmune Pancreatitis: A Multireader Study Am. J. Roentgenol., February 1, 2008; 190(2): 280 - 286. [Abstract] [Full Text] [PDF]
|
|
Read all eLetters
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | CURRENT ISSUE | PAST ISSUES | COLLECTIONS | HELP | SEARCH |
|
|||||
|
Copyright 1995-2006, Canadian Medical Association. All rights reserved. ISSN 1488-2329
(e) 0820-3946 (p)
All editorial matter in CMAJ represents the opinions of the authors and not necessarily those of the Canadian Medical Association. |
|||||
