IgG4 immunostaining of duodenal papillary biopsy specimens may be useful for supporting a diagnosis of autoimmune pancreatitis

The therapeutic strategy for autoimmune pancreatitis is subject to the endoscopic features of the duodenal papilla

Autoimmune pancreatitis (AIP) often presents with a swollen duodenal papilla, however, the clinical significance of the duodenal papilla in AIP has not been fully elucidated. Data have shown swollen duodenal papillae shaped like a pear and/or with a submucosal tumor having IgG4-bearing plasma cells. Immunohistopathology has potentially verified duodenal papillitis associated with AIP. FOXP3-positive lymphocytes are also recognized in AIP. AIP has shown spontaneous remission and relapse irrelevance to corticosteroid therapy. The results of a multivariate analysis revealed the absence of a swollen duodenal papilla as the only significant independent factor predictive of spontaneous remission in AIP cases. In addition, the results of another multivariate analysis revealed the presence of a swollen duodenal papilla and the presence of extrapancreatic lesions as the significant independent factors predictive of relapse in these cases. Results suggest that the lack of a swollen duodenal papilla is a predictive factor for spontaneous remission, and thus negates the need to administer corticosteroids in those AIP patients. In contrast, a swollen duodenal papilla and the presence of extrapancreatic lesions are risk factors for relapse, and those AIP patients are candidates for maintenance corticosteroid therapy to reduce relapse. Therefore, the therapeutic strategy such as the indication for corticosteroid administration is subject to the endoscopic features of the duodenal papilla.

Diagnosis and treatment of autoimmune pancreatitis

PURPOSE OF REVIEW

To summarize the existing knowledge of autoimmune pancreatitis (AIP) and to review the progress made in the diagnosis and treatment of AIP in the past year.

RECENT FINDINGS

The term 'AIP' appears to encompass at least two distinct subtypes, type 1 and type 2. Type 1 AIP is the pancreatic manifestation of a systemic fibroinflammatory disease called immunoglobulin G4-associated systemic disease. Type 2 AIP affects younger patients, does not have a gender predilection and is associated with normal serum immunoglobulin G4 levels. Existing criteria are geared toward diagnosis of type 1; type 2 AIP can be definitively diagnosed only on pancreatic histology. Both subtypes respond to corticosteroid therapy. However, there are no standardized protocols for initial treatment or management and prevention of relapses in AIP. A novel antibody for AIP has recently been identified and its performance needs validation from other centers. Newly published strategies for differentiating AIP from pancreatic cancer are available.

SUMMARY

AIP is a rare disease whose recognition and understanding are evolving. Much needs to be elucidated with regard to its cause, pathogenesis, treatment of relapse and long-term outcomes. A multidisciplinary team, familiar with the disease, is critical in making the correct diagnosis.

IgG4-related sclerosing disease: a critical appraisal of an evolving clinicopathologic entity

An elevated serum titer of immunoglobulin G4 (IgG4), the least common (3% to 6%) of the 4 subclasses of IgG, is a surrogate marker for the recently characterized IgG4-related sclerosing disease. The syndrome affects predominantly middle-aged and elderly patients, with male predominance. The patients present with symptoms referable to the involvement of 1 or more sites, usually in the form of mass lesions. The prototype is IgG4-related sclerosing pancreatitis (also known as autoimmune pancreatitis), most commonly presenting as painless obstructive jaundice with or without a pancreatic mass. Other common sites of involvement are the hepatobiliary tract, salivary gland, orbit, and lymph node, but practically any organ-site can be affected, such as retroperitoneum, aorta, mediastinum, soft tissue, skin, central nervous system, breast, kidney, prostate, upper aerodigestive tract, and lung. The patients usually have a good general condition, with no fever or constitutional symptoms. Common laboratory findings include raised serum globulin, IgG, IgG4, and IgE, whereas lactate dehydrogenase is usually not raised. Some patients have low titers of autoantibodies (such as antinuclear antibodies and rheumatoid factor). The disease often shows excellent response to steroid therapy. The natural history is characterized by the development of multiple sites of involvement with time, sometimes after many years. However, the disease can remain localized to 1 site in occasional patients. The main pathologic findings in various extranodal sites include lymphoplasmacytic infiltration, lymphoid follicle formation, sclerosis and obliterative phlebitis, accompanied by atrophy and loss of the specialized structures of the involved tissue (such as secretory acini in pancreas, salivary gland, or lacrimal gland). The relative predominance of the lymphoplasmacytic and sclerotic components results in 3 histologic patterns: pseudolymphomatous, mixed, and sclerosing. Immunostaining shows increased IgG4+ cells in the involved tissues (>50 per high-power field, with IgG4/IgG ratio >40%). The lymph nodes show multicentric Castleman disease-like features, reactive follicular hyperplasia, interfollicular expansion, or progressive transformation of germinal centers, with the unifying feature being an increase in IgG4+ plasma cells on immunostaining. The nature and pathogenesis of IgG4-related sclerosing disease are still elusive. Occasionally, the disease can be complicated by the development of malignant lymphoma and possibly carcinoma.