Pancreatic Cancer? Think Again

Introduction: IgG4 associated cholangiopathy can present with a broad spectrum of disease from asymptomatic cases to weight loss and jaundice. We present a case of a self-resolving pancreatic head mass that we believe is secondary to autoimmune cholangiopathy. Case Description/Methods: A 68 yo female with DMII & HTN, presented with recent epigastric pain, 10-lb weight loss, & CT A/P with fullness in the pancreatic head. MRCP revealed a 31x29 mm pancreatic head mass causing narrowing and upstream dilation of CBD, concerning for pancreatic cancer. LFTs were normal with no evidence of obstruction. EUS revealed a 45 × 34 mm calcified, lobulated, hypoechoic & hyperechoic mass with a necrotic component in the pancreatic head with the mass invading the portal vein and CBD. FNA revealed pancreatic acinar & ductal tissue with chronic inflammation and fibrosis (chronic pancreatitis), negative for carcinoma. Immunohistochemical analysis with IgG4 and MUM1 ruled out IgG-4 related disease. Of note, CA 19-9 was slightly elevated. Subsequent CT scan revealed new BD dilation with an area of transition in the pancreatic head. Given the change, another EUS was completed. PET revealed mild uptake from the pancreatic head mass. 2nd FNA sampling also revealed chronic pancreatitis and was negative for malignancy. MRCP surprisingly revealed significant improvement of the PD obstruction but new strictures of the CBD and BD compared to prior. This constellation of findings raised the possibility of autoimmune cholangiopathy. One week later, the patient developed dark urine, epigastric cramping & pale stools. Labs were notable for T Bili 6.4, AST 117, ALT 208, & Alk Phos 266 (all normal 2 weeks prior). CT A/P revealed a new ill-defined, masslike heterogeneously enhancing area at the hilum causing CBD narrowing but improvement in the pancreatic head mass. Given her recent history of pancreatic head mass which was resolving, her picture was concerning for autoimmune cholangiopathy. She was started on prednisone, and LFTs significantly improved. Prednisone was tapered slowly and azathioprine initiated. Discussion: Understanding autoimmune cholangiopathy is a slowly evolving process. This case highlights the need for physicians to maintain a broad differential and the occasional difficulty with diagnosis given serum IgG4 levels and pathology are not sensitive. Thankfully, IgG4 associated disease typically responds quickly and well to steroid therapy, allowing physicians to be fairly confident in their diagnosis post-steroid initiation.