P2172 - Unusual Presentation of Autoimmune Pancreatitis With Adenocarcinoma of the Head of the Pancreas

Alok Shrestha, DO¹, Monica Multani, DO¹, Andrew Dam, DO², Andrew Shenouda, BSc³, George Shenouda, DO¹, Chandra Sanwal, DO¹, Sohan Dongol, BSPH⁴, Karthik Mohan, DO^1
1Larkin Community Hospital, South Miami, FL; ²Larkin Community Hospital, Hialeah, FL; ³Trinity School of Medicine, Roswell, GA; ⁴Georgia State University, Atlanta, GA

Introduction: Several pancreatic lesions can mimic pancreatic ductal adenocarcinoma (PDA). Autoimmune pancreatitis (AIP) is a form of pancreatitis that shares many characteristics of PDA and can present a complex diagnostic dilemma.

Case Description/Methods: A 73-year-old male with a history of hypertension and former tobacco abuse was admitted to the hospital for abdominal pain for 3 months that was exacerbated with eating and bending forward. He complained of poor appetite and denied weight loss. Recent PET-CT scan showed FDG uptake at the head of the pancreas with a 2.2 x 2.1 cm soft tissue mass and multiple abnormal retroperitoneal lymph nodes. CA 19-9 was elevated at 85 units/mL. Laparoscopic biopsies of the pancreatic mass, lymph nodes, and liver were negative for malignancy. However, pancreatitis with diffuse and rich lymphoplasmacytic inflammatory infiltrates with greater than 10 IgG4-positive plasma cells per HPF, reactive ductal epithelial cells, and obliterative phlebitis were noted. He was diagnosed with AIP and discharged for outpatient management but was readmitted four months later for worsening abdominal pain and 30 pounds weight loss. Serum IgG4 was elevated at 146 mg/dL and CA 19-9 was greater than 920 units/mL. A repeat CT scan showed an enlarged lobulated 4.2 x 4.5 x 5.1 cm necrotic pancreatic head mass with atrophy of the pancreatic body and tail and peripancreatic adenopathy. Biopsy of the mass with EUS-FNA revealed high grade adenocarcinoma. Preoperative imaging showed no evidence of vascular invasion, however invasion of the SMV was found intraoperatively. The patient’s clinical course worsened, and he opted for hospice care.

Discussion: In this case, the initial presentation was suspicious for pancreatic cancer, however, the first pancreatic biopsy was negative for malignancy and highly suggestive of AIP. Although initial CA 19-9 was marginally elevated, it is nondiagnostic and may occur in acute inflammation. The diagnosis of PDA was determined on the second biopsy and supported by the markedly elevated CA 19-9. Currently, there is no conclusive evidence of AIP as an increased risk for PDA. While cases of concurrent AIP and PDA have been reported, the initial biopsies in this case were negative for cancer. Our patient is likely an outlier case who was diagnosed with PDA within 4 months after the initial diagnosis of AIP. Patients diagnosed with AIP and pancreatic mass should be closely followed and managed.



Disclosures:


Alok Shrestha, DO¹, Monica Multani, DO¹, Andrew Dam, DO², Andrew Shenouda, BSc³, George Shenouda, DO¹, Chandra Sanwal, DO¹, Sohan Dongol, BSPH⁴, Karthik Mohan, DO¹. P2172 - Unusual Presentation of Autoimmune Pancreatitis With Adenocarcinoma of the Head of the Pancreas, ACG 2021 Annual Scientific Meeting Abstracts. Las Vegas, Nevada: American College of Gastroenterology.