Autoimmune pancreatitis: a challenging diagnostic puzzle for clinicians

Pancreas Solid Tumors

Solid tumors of the pancreas encompass a variety of diagnoses with treatments ranging from observation to major abdominal surgery. Pancreatic ductal adenocarcinoma remains one of the most common and most lethal of these differential of diagnoses and requires a multimodality approach through a multidisciplinary team of specialists. This article reviews the classification, clinical presentation, and workup in differentiating solid tumors of the pancreas and serves as an additional tool for general surgeons faced with such a clinical finding, from a surgical oncology perspective.

From Pathogenesis, Clinical Manifestation, and Diagnosis to Treatment: An Overview on Autoimmune Pancreatitis

Autoimmune pancreatitis (AIP) is a special type of chronic pancreatitis which is autoimmune mediated. The international consensus diagnostic criteria (ICDC) 2011 proposed two types of AIP: type I is associated with histological pattern of lymphoplasmacytic sclerosing pancreatitis (LPSP), characterized by serum IgG4 elevation, whereas type 2 is named idiopathic duct-centric pancreatitis (IDCP), with granulocytic epithelial lesion (GEL) and immunoglobulin G4 (IgG4) negative. The pathogenic mechanism is unclear now; based on genetic factors, disease specific or related antigens, innate and adaptive immunity may be involved. The most common clinical manifestations of AIP are obstructive jaundice and upper abdominal pain. The diagnosis can be made by a combination of parenchymal and ductal imaging, serum IgG4 concentrations, pancreatic histology, extrapancreatic disease, and glucocorticoid responsiveness according to ICDC 2011. Because of the clinical and imaging similarities with pancreatic cancer, general work-up should be done carefully to exclude pancreatic malignant tumor before empirical trial of glucocorticoid treatment. Glucocorticoid is the most common drug for AIP to induce remission, while there still exists controversy on steroid maintenance and treatment for relapse. Further studies should be done to identify more specific serum biomarkers for AIP, the pathogenic mechanisms, and the treatment for relapse.

Pancreatic Ductal Adenocarcinoma and Its Variants

Pancreatic cancer represents the seventh leading cause of cancer death in the world, responsible for more than 300,000 deaths per year. The most common tumor type among pancreatic cancers is pancreatic ductal adenocarcinoma, an infiltrating neoplasm with glandular differentiation that is derived from pancreatic ductal tree. Here we present and discuss the most important macroscopic, microscopic, and immunohistochemical characteristics of this tumor, highlighting its key diagnostic features. Furthermore, we present the classic features of the most common variants of pancreatic ductal adenocarcinoma. Last, we summarize the prognostic landscape of this highly malignant tumor and its variants.

Immunoglobulin G4-related pancreatic and biliary diseases

BACKGROUND

Autoimmune pancreatitis and autoimmune cholangitis are new clinical entities that are now recognized as the pancreatico-biliary manifestations of immunoglobulin (Ig) G4-related disease.

OBJECTIVE

To summarize important clinical aspects of IgG4-related pancreatic and biliary diseases, and to review the role of IgG4 in the diagnosis of autoimmune pancreatitis (AIP) and autoimmune cholangitis (AIC).

METHODS

A narrative review was performed using the PubMed database and the following keywords: "IgG4", "IgG4 related disease", "autoimmune pancreatitis", "sclerosing cholangitis" and "autoimmune cholangitis". A total of 955 articles were retrieved; of these, 381 contained relevant data regarding the IgG4 molecule, pathogenesis of IgG-related diseases, and diagnosis, management and long-term follow-up for patients with AIP and AIC. Of these 381 articles, 66 of the most pertinent were selected.

RESULTS

The selected studies demonstrated the increasing clinical importance of both AIP and AIC, which can mimic pancreatic cancer and cholangiocarcinoma, respectively. IgG4 titration in tissue or blood cannot be used alone to diagnose all IgG4-related diseases; however, it is often a useful adjunct to clinical, radiological and histological features. AIP and AIC respond to steroids; however, relapse is common and long-term maintenance treatment often required.

CONCLUSIONS

A review of the diagnosis and management of both AIC and AIP is timely and pertinent to clinical practice because the amount of information regarding these conditions has increased substantially in the past few years, resulting in significant impact on the clinical management of affected patients.

Localized type 1 autoimmune pancreatitis superimposed upon preexisting intraductal papillary mucinous neoplasms

A 70-year-old woman was found to have 2 cystic lesions in the head of the pancreas on abdominal ultrasonography during a routine medical examination. Endoscopic ultrasonography (EUS) and magnetic resonance cholangiopancreatography showed multilocular cysts in the head of the pancreas without dilation of the main pancreatic duct. The patient was followed-up semiannually with imaging studies for suspected branch duct-type intraductal papillary mucinous neoplasm (IPMN). At 3 years after initial presentation, hypoechoic lesions were observed around each pancreatic cyst by EUS. Diffusion-weighted imaging showed high-intensity regions corresponding to these lesions. Therefore, a diagnosis of invasive carcinoma derived from IPMN could not be excluded, and subtotal stomach-preserving pancreaticoduodenectomy was performed. The macroscopic examination of the surgical specimen showed whitish solid masses in the head of the pancreas, with multilocular cysts within each mass. Microscopically, each solid mass consisted of inflammatory cells such as lymphocytes and plasma cells. Furthermore, immunochemical staining revealed immunoglobulin G4-positive cells, and many obliterating phlebitides were observed. The cysts consisted of mucus-producing epithelial cells and showed a papillary growth pattern. Based on these findings, we diagnosed multiple localized type 1 autoimmune pancreatitis occurring only in the vicinity of the branch duct-type IPMN.

Short-term and long-term outcomes for patients with autoimmune pancreatitis after pancreatectomy: a multi-institutional study

BACKGROUND

Autoimmune pancreatitis (AIP) is a rare subtype of chronic pancreatitis that may mimic adenocarcinoma of the pancreas. The aim of this study was to evaluate the short-term and long-term outcomes of pancreatectomy for patients with AIP.

METHODS

In this multi-institutional study, we identified all patients who underwent pancreatectomy for AIP from 1986 to 2011. AIP was confirmed by pathology review. Clinical presentation, operative details, and postoperative outcomes were analyzed.

RESULTS

Seventy-four patients (median age, 60 years; 69 % male) with AIP underwent pancreatectomy. The main indication for operation was concern for malignancy (n = 59, 80 %). No patients were found to have pancreatic adenocarcinoma on final pathology. Major complications occurred in ten (14 %) patients, with one perioperative death (1 %). Clinically relevant (grade B/C) pancreatic fistulae occurred in two patients. No patients required reoperation for AIP and 11 (17 %) patients developed recurrent AIP.

CONCLUSION

Although we do not advocate pancreatectomy for AIP, strong suspicion of malignancy may require an operation in selected patients. For patients with AIP, pancreatectomy resulted in few pancreatic fistulae, a low rate of re-intervention, and a 17 % recurrence rate.

B-cell lymphoma presenting as acute pancreatitis

BACKGROUND

Pancreatic lymphoma is uncommon, representing less than 0.5% of pancreatic tumors, with diffuse large B-cell lymphoma being the predominant histotype. Acute pancreatitis associated with pancreatic lymphoma is rare.

CASE REPORT

We describe a case of synchronous pancreatic and pulmonary localizations of non-Hodgkin's lymphoma in a 42-year-old man who presented with acute pancreatitis. Acute pancreatitis resolved after standard treatment with a fasting regimen, gabexate mesilate and parenteral nutrition. However, ultrasound scan and abdominal computed tomography revealed two hypoechogenic areas within the pancreas, and chest X-ray film showed a pulmonary infiltrate in the right basal field. A percutaneous fine-needle aspiration biopsy of the pulmonary infiltrate under computed tomography guidance demonstrated a diffuse infiltration by atypical lymphoid cells positive for leukocyte common antigen, CD20 and CD30. Percutaneous fine-needle aspiration biopsy under ultrasound guidance of the pancreatic mass confirmed the diagnosis of diffuse large B-cell lymphoma. The patient was classified as stage IV-A, low-intermediate risk and received 6 cycles of chemotherapy.

CONCLUSION

This is the first case of large B-cell lymphoma presenting with concomitant primary pancreatic and pulmonary involvement. Pancreatic lymphoma is uncommon and represents a rare cause of acute pancreatitis. The discovery of a pancreatic mass needs pathologic diagnosis to distinguish lymphoma from carcinoma or autoimmune pancreatitis. and IAP.

Management strategies for autoimmune pancreatitis

INTRODUCTION

Autoimmune pancreatitis (AIP) is a newly developed concept for a peculiar type of pancreatitis, and at present is recognized as a pancreatic lesion reflecting IgG4-related systemic disease. It is of utmost importance to differentiate AIP from pancreatic cancer to avoid unnecessary surgery.

AREAS COVERED

The current management strategies for AIP, including its clinical features, diagnostic criteria, clinical subtypes, steroid therapy and prognosis are discussed, based on our 66 AIP cases and papers searched in PubMed from 1992 to March 2011, using the term 'autoimmune pancreatitis'. A new clinicopathological entity, an 'IgG4-related sclerosing disease' is also mentioned.

EXPERT OPINION

AIP should be considered in the differential diagnosis in elderly male patients presented with obstructive jaundice and pancreatic mass. Steroids are a standard therapy for AIP, but their regimen including maintenance therapy should be evaluated in prospective trials.

[Clinical characteristics of autoimmune pancreatitis]

Korean autoimmune pancreatitis (AIP) criteria 2007 was aimed to diagnose the wide spectrum of AIP with high sensitivity. The most crucial issue when caring for patients with suspected AIP is to differentiate AIP from pancreatic cancer. Pancreatic cancer can be distinguished from AIP by pancreatic imaging, measurement of serum IgG4 levels, endoscopic ultrasound guided fine needle aspiration and trucut biopsy, and steroid trial. Autoimmune pancreatitis is a rare systemic fibroinflammatory disease which can affect not only the pancreas, but also a variety of organs such as the bile ducts, salivary glands, retroperitoneum, and lymph nodes. Organs affected by AIP have a lymphoplasmacytic infiltrate rich in IgG4-positive cells. This inflammatory process responds dramatically to oral steroid therapy. Granulocytic epithelial lesion (GEL) positive AIP patients differ from GEL negative AIP patients in clinical features such as equal gender ratio, younger mean age, no increase in serum IgG4, no association with extrapancreatic involvement, no relapse, and frequent association with inflammatory bowel disease. Further investigation is needed to clarify the pathogenic mechanisms including more definite serological markers for theses two entities.

A practical approach to the diagnosis of autoimmune pancreatitis

Autoimmune pancreatitis is a disease characterized by specific pathological features, different from those of other forms of pancreatitis, that responds dramatically to steroid therapy. The pancreatic parenchyma may be diffusely or focally involved with the possibility of a low-density mass being present at imaging, mimicking pancreatic cancer. Clinically, the most relevant problems lie in the diagnosis of autoimmune pancreatitis and in distinguishing autoimmune pancreatitis from pancreatic cancer. Since in the presence of a pancreatic mass the probability of tumour is much higher than that of pancreatitis, the physician should be aware that in focal autoimmune pancreatitis the first step before using steroids is to exclude pancreatic adenocarcinoma. In this review, we briefly analyse the strategies to be followed for a correct diagnosis of autoimmune pancreatitis.

Endoscopic ultrasonography findings in autoimmune pancreatitis

Endoscopic ultrasonography is an established diagnostic tool for pancreatic masses and chronic pancreatitis. In recent years there has been a growing interest in the worldwide medical community in autoimmune pancreatitis (AIP), a form of chronic pancreatitis caused by an autoimmune process. This paper reviews the current available literature about the endoscopic ultrasonographic findings of AIP and the role of this imaging technique in the management of this protean disease.

Italian consensus guidelines for chronic pancreatitis

This paper gives practical guidelines for diagnosis and treatment of chronic pancreatitis. Statements have been elaborated by working teams of experts, by searching for and analysing the literature, and submitted to a consensus process by using a Delphi modified procedure. The statements report recommendations on clinical and nutritional approach, assessment of pancreatic function, treatment of exocrine pancreatic failure and of secondary diabetes, treatment of pain and prevention of painful relapses. Moreover, the role of endoscopy in approaching pancreatic pain, pancreatic stones, duct narrowing and dilation, and complications was considered. Recommendations for most appropriate use of various imaging techniques and of ultrasound endoscopy are reported. Finally, a group of recommendations are addressed to the surgical treatment, with definition of right indications, timing, most appropriate procedures and techniques in different clinical conditions and targets, and clinical and functional outcomes following surgery.