Pancreatic Cancer Mimicking Relapse of Autoimmune Pancreatitis: Case Reports

Abstract

INTRODUCTION: Although pancreatic cancer rarely co-occurs with autoimmune pancreatitis (AIP), distinguishing between AIP relapse and pancreatic cancer remains difficult, potentially leading to delayed diagnosis. A recent nationwide survey in Japan indicated that pancreatic cancer underlies a significant proportion of cancer-related deaths among patients with AIP. CASE PRESENTATION: A 76-year-old woman with AIP, diagnosed based on focal pancreatic body enlargement and elevated IgG4, experienced multiple steroid-responsive relapses over 8 years. While tapering steroids, a new pancreatic nodule was detected on MRI, which was characterized by high signal intensity on diffusion-weighted imaging. Although the initial EUS-FNA was negative for carcinoma, a repeat biopsy 10 months later confirmed pancreatic cancer. Both patients underwent laparoscopic or robotic distal pancreatectomy with lymphadenectomy, and histopathological analysis confirmed pancreatic cancer arising in severely AIP-affected pancreatic tissue. CONCLUSIONS: In patients showing clinical or radiological worsening during AIP follow-up, repetitive diagnostic evaluations are warranted to facilitate the timely detection of underlying pancreatic cancer.