P2947 - IgG4-Related Hepatic Pseudotumor Masquerading as a Klatskin Tumor

Jennifer Yoon, MD¹, Steve Hu, MD², Adnan Ameer, MD^3
1UCSF Fresno, Fresno, CA; ²University of California San Francisco Fresno, Fresno, CA; ³UCSF Fresno/CCFMG, Fresno, CA

Introduction: Inflammatory pseudotumors (IPT) are benign mass-forming lesions that consist of inflammatory cells, fibrous tissue, and myofibroblasts and are often mistaken for malignant tumors. Hepatic IPTs can be due to infection, congenital disease, gallstones, chronic biliary inflammation, and IgG4 related disease (IgG4-RD). IgG4-related hepatic IPTs are uncommon; differentiation from malignant tumors is crucial for management and avoiding unnecessary resection. Here, we describe a case of IgG4-related hepatic IPT mimicking a Klatskin tumor.

Case Description/Methods: A 59-year-old male with HIV on HAART presented with abdominal pain and jaundice. He had an amorphous appearing pancreatic head mass with dilated intra and extrahepatic bile ducts on computed tomography(CT) with serum IgG4 of 354 mg/dL (4-86 mg/dL). EUS-guided biopsy of the pancreatic head mass and an ERCP were performed; he was diagnosed with type I autoimmune pancreatitis by histology and required stenting of a distal biliary stricture along with prednisone taper, resulting in subsequent resolution.

Two years later, he again presented with abdominal pain and jaundice. His IgG4 was 458.9 mg/dL. CT showed a mass-like mural thickening of the central hepatic biliary ducts concerning for Klatskin tumor (Figure 1). An irregular hypoechoic mass in the porta hepatitis was seen during EUS-guided FNB, histopathology revealed a IgG4-associated hepatic IPT. ERCP again showed a distal biliary stricture and brushings were unremarkable. To confidently rule out malignancy, the patient underwent CT-guided biopsy of the hilar mass. Histopathology corroborated the findings from the EUS-guided FNB. He was again treated with a prednisone taper with complete resolution of the pseudotumor on follow-up imaging.

Discussion: IgG4-RD is an autoimmune, fibro-inflammatory disease that can manifest in any organ and often mimics malignancy. It is predominant in middle-aged to elderly men and commonly affects the pancreas, salivary glands, orbit, kidneys, and retroperitoneum. The mainstay of therapy is systemic steroids. IgG4 related hepatic IPTs usually develop in the hepatic hilum and can present similarly to hilar or intrahepatic cholangiocarcinomas on imaging. Difficulty in distinguishing between hepatic IPTs and malignant tumors have resulted in unwarranted hepatic resections (Table 1). A high degree of clinical suspicion is imperative in appropriate management and preventing patient harm.




Disclosures:


Jennifer Yoon, MD¹, Steve Hu, MD², Adnan Ameer, MD³. P2947 - IgG4-Related Hepatic Pseudotumor Masquerading as a Klatskin Tumor, ACG 2021 Annual Scientific Meeting Abstracts. Las Vegas, Nevada: American College of Gastroenterology.