The role of serological biomarkers in the diagnosis and management of autoimmune pancreatitis

ABSTRACT

Introduction

Autoimmune pancreatitis (AIP) is a fibroinflammatory disease of the pancreas. Type 1 AIP is the pancreatic manifestation of a systemic IgG4-related disease and is associated with serum elevation of IgG4, tissue infiltration of IgG4-positive plasma cells, and multiorgan involvement. Although serum IgG4 elevation is considered a useful diagnostic tool, the concomitant presence of more diagnostic criteria is needed to achieve diagnosis. No other biomarkers have been approved in clinical practice in type 1 AIP. Type 2 AIP is a pancreatic-specific disease associated with inflammatory bowel disease. No specific biomarkers for type 2 AIP have been identified.

Areas covered

The role of serum IgG4 in the diagnosis, management and follow-up of patients with type 1 AIP. Moreover, data on other emerging biomarkers for type 1 and 2 AIP have been reported.

Expert Opinion

The diagnosis of AIP is challenging in clinical practice, especially for focal forms without multiorgan involvement, where distinction from pancreatic cancer can be difficult. Despite the strong association with type 1 AIP, serum IgG4 should only be measured when the suspicion for the disease is high, considering its limited sensitivity. New biomarkers with high diagnostic yield for both type 1 and type 2 AIP are needed.

KEYWORDS:

• IgG4-related disease
• autoimmune pancreatitis
• IgG4
• diagnosis

Article highlights

• Serum IgG4 is the only available biomarker for the diagnosis of type 1 AIP.

• Other promising diagnostic biomarkers have been proposed and studied, but definitive data are still lacking.

• Serum IgG4 should never be used alone to diagnose AIP or to differentiate AIP from pancreatic cancer.

• Serum IgG4 is included in the IgG4-related disease responder index.

• A decrease in serum IgG4 and of IgG4-related diseases responder index post steroid treatment are associated with a low risk of relapse in patients with type 1 AIP.

• A combination of different clinical, radiological, pathological, and serological criteria is needed to achieve AIP diagnosis.

• No biomarkers for type 2 AIP have been identified yet.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

This paper was not funded.