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

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.

The features and clinical outcomes of inflammatory bowel disease associated with autoimmune pancreatitis: A greater awareness is needed.

ABSTRACT: The prevalence of inflammatory bowel disease (IBD) has been described in 5% to 40% of autoimmune pancreatitis (AIP) patients. The aim of our study was to evaluate the prevalence, endoscopic features, and outcome of IBD in association with AIP.A retrospective analysis including all consecutive patients with AIP and a histological diagnosis of IBD from 2010 to 2020 was performed. Demographical data, AIP, and IBD features, as well as clinical course, were recorded.Among 267 AIP patients, 45 were diagnosed with ulcerative colitis (UC) (27 men, mean age 31.6), all with a diagnosis of type 2 AIP. The most frequent presentation of AIP was acute pancreatitis (55.5%). Both diffuse (51.1%) and focal (48.9%) pancreatic involvement were observed. The AIP relapse rate was 11.1% over a mean follow-up of 55 months. In 69% of patients, the interval time between the diagnosis of AIP and UC was <1 year. When UC was present at AIP onset, UC was in clinical remission in 50% of patients. Fecal calprotectin levels, when available, were elevated in 86.6% of these patients. Mostly, mild-moderate pancolitis was initially diagnosed (55.5%). During follow-up, escalation therapy for UC was required in 40% of patients after a mean time of 45 months. Two patients (4.4%) underwent colectomy.The prevalence of UC in AIP patients was 17%. Mild pancolitis with a low rate of colectomy was found. Greater awareness is needed to avoid a delayed diagnosis of UC, and the dosage of fecal calprotectin levels could have a role in this setting.