There is no single test to confirm IgG4-RD and diagnosis depends on the combination of clinical presentation, inflammatory masses on cross sectional imaging, a raised serum IgG4 and characteristic histopathological features which comprise a lymphoplasmacytic infiltrate rich in IgG4+ plasma cells, obliterative phlebitis and storiform fibrosis (Deshpande et al., 2012). Diagnostic criteria to aid decision-making have been agreed on by international consensus for both pancreatic and extra-pancreatic disease (Chari et al., 2006; Okazaki et al., 2017
Diag. Immunostaining of the bile duct showing infiltrating IgG4-positive plasma cells (DAB-positive dark brown).
Diag. CT abdomen and pelvis with contrast showing a mass at the head of the pancreas in a patient with Autoimmune Pancreatitis Type 1. The mass obstructs the distal common bile duct with proximal intra hepatic duct dilatation and mild pancreatic duct dilatation.
- Clinical presentation
- Serum IgG4 levels
- Imaging studies
- Biopsy evidence
- Response to treatment, including corticosteroids
Clinicians can use one of the following criteria to see if a patient may have a diagnosis of IgG4-RD
1. HISORt Criteria for autoimmune pancreatitis
2. Japanese CDC for systemic disease
3. Boston Histopathological Criteria
An IgG4 Responder Index has been developed and validated internationally to monitor disease activity