Since December 2019, coronavirus disease 2019 (COVID-19), caused by the severe respiratory syndrome coronavirus 2 (SARS-CoV-2), has affected more than 124 million people worldwide as of 23/3/2021. While studies on the outcomes of inflammatory bowel disease (IBD) (an important gastroenterological disease requiring immunosuppressive therapies for treatment) patients with COVID-19 have been published recently, little is known about the impact of COVID-19 on the clinical outcomes and management of IgG4 related disease patients with pancreatobiliary involvement. Because the number of IgG4 patients with pancreatobiliary involvement cared by individual centers and the prevalence of COVID-19 infection in different geographical regions vary, we propose to conduct a multicenter retrospective study to further evaluate the impact of COVID-19 on the clinical outcomes and management of IgG4 related disease patients with pancreatobiliary involvement.

Since December 2019, coronavirus disease 2019 (COVID-19), caused by the severe respiratory syndrome coronavirus 2 (SARS-CoV-2), has affected more than 124 million people worldwide as of 23/3/2021. While many COVID-19 patients have been reported to have a milder clinical course, old age and comorbidities including cardiovascular disease, chronic lung conditions, obesity, and diabetes have been associated with a more severe disease course and higher mortality. Moreover, patients with chronic immune-mediated inflammatory diseases are at risk of viral infections either related to their underlying immune dysfunction or the immunosuppressive therapy that they receive for the chronic inflammatory conditions.

IgG4 related disease is an increasingly recognized immune-mediated condition that may resemble many malignant, infectious or inflammatory diseases. It is characterized by tumor-like lesions, with histopathological features of lymphoplasmacytic infiltrate rich in IgG4-positive plasma cells, obliterative phlebitis, storiform fibrosis, and, often but not always, elevated serum IgG4 concentrations.

While studies on the outcomes of inflammatory bowel disease (IBD) (an important gastroenterological disease requiring immunosuppressive therapies for treatment) patients with COVID-19 have been published recently, little is known about the impact of COVID-19 on the clinical outcomes and management of IgG4 related disease patients with pancreatobiliary involvement. Because the number of IgG4 patients with pancreatobiliary involvement cared by individual centers and the prevalence of COVID-19 infection in different geographical regions vary, we propose to conduct a multicenter retrospective study to further evaluate the impact of COVID-19 on the clinical outcomes and management of IgG4 related disease patients with pancreatobiliary involvement.

Inclusion Criteria:

1. Age 18 or above

2. IgG4 related disease patients with pancreatobiliary involvement receiving care in the GI clinic of the participating centers

3. The diagnosis of IgG4 related disease was made either by:

   1. an elevated serum IgG4 serology level with typical features of pancreatobiliary involvement on imaging (eg, CT / MRI), and/or endoscopic ultrasound (EUS), and/or endoscopic retrograde cholangiopancreatography (ERCP), or
   2. an elevated serum IgG4 serology level with typical histopathologic features of the disease (eg, lymphoplasmacytic infiltration, obliterative phlebitis, and storiform fibrosis) on surgical pathology (eg, biopsy during surgery or surgical resection specimen) or endoscopic biopsies (eg, EUS guided fine needle biopsy).

Exclusion Criteria:

1) Patients who have an alternative diagnosis (i.e., non-IgG4 disease) despite an elevated serum IgG4 level

IgG4 patients with pancreatobiliary system involvement receiving care in the gastroenterology (GI) clinic in the participating centers fulfilling the inclusion criteria listed below and without exclusion criteria would be included in the study.