Introduction: IgG4-related disease (IGRD) is a multi-organ immune-mediated condition that mimics infection, malignancy, and inflammatory disorders. It can affect any organ of the body with the most commonly known presentation being type 1 autoimmune pancreatitis (AIP). However, IGRD can also rarely present as IgG4 sclerosing cholangitis (ISC). The mean age at diagnosis of ISC is 67 years with a male-to-female ratio of 3:1. The diagnosis relies on clinical correlation with imaging and biopsy because ISC can be misdiagnosed as primary sclerosing cholangitis (PSC).
Case Description/Methods: We present a 68 year old male with chronic gastritis, hiatal hernia, and prior cholecystectomy presenting with two weeks of epigastric pain. The admission liver function tests (LFT) were as follows: total bilirubin (Tbili) 3.1 mg/dL, direct bilirubin 1.58 mg/dL, alkaline phosphatase (ALP) 304 units/L, ALT 584 units/L, AST 447 units/L, lipase 2566 units/L. CT abdomen with IV contrast showed biliary dilation, prominent common bile duct (CBD) with wall enhancement. Magnetic resonance cholangiopancreatography showed focal narrowing and inflammation at the pancreatic head. Subsequently, the patient underwent endoscopic retrograde cholangiopancreatography, CBD stent placement, and biliary brush tissue sampling that was non-diagnostic. Later, endoscopic ultrasound fine-needle biopsy of biliary-pancreatic tissue ruled out malignancy. AIP was diagnosed by dense storiform fibrosis and lymphocytic infiltrate of IgG4-positive plasma cells on pathology along with high serum IgG4 (516 mg/dL). He was discharged on tapered prednisone but was readmitted months later for recurrence of similar complaints and elevated LFTs with a cholestatic pattern. Suspicions for acute cholangitis prompted ERCP with Spyglass cholangioscopy revealing erythematous proximal to mid-CBD. Biopsy showed inflamed ulcerated biliary mucosa with IgG4-positive plasma cells. PSC was ruled out by a negative anti-smooth muscle antibody. Response to prednisone reinforced diagnosis of ISC.
Discussion: ISC is a rare, under-recognized manifestation of IGRD. The HISORt criteria used for AIP can be utilized to diagnose ISC. This includes histology of >10 IgG4-positive plasma cells per high power field, storiform fibrosis, bile duct strictures on imaging, serology (IgG4 >135 mg/dL), other organ involvement (like AIP), and steroid therapy response (improved LFT, strictures, or both). Increased awareness regarding ISC is paramount as the condition can often be misdiagnosed for PSC.
