IgG4 Related Disease Presenting as Simultaneous Pancreatic and Lung Mass Mimicking Malignancy

Introduction and importance: IgG4-RD (IgG4 related disease) can be challenging as it lead to the formation of a “mass” within organs often misdiagnosed malignancies. Focal mass forming types AIP (auto-immune pancreatitis) in present with obstructive jaundice pancreatic mass. lung also nodules mimicking carcinoma lung. Case presentation: We report 70 years old Asian male, presented both simultaneously patient underwent whipple procedure was found that lesion pancreas is not malignancy but IgG4-RD. Then got bigger symptoms coughing weight loss, then biopsy confirmed IgG-RD responds well rituximab. Clinical discussion: Malignancy highly suspected given presentation certain organs. It very difficult differentiate from cancer. Most patients had resection done order exclude malignancy. Lung involvement has been reported which presents autoimmune pancreatitis. However, discussion on coexistence mass-like lacking literature. A thorough preoperative process aimed at ruling out differential diagnoses avoid false extensive surgery. Clinicians should remain aware various presentations ensure correct diagnosis. Conclusion: An awareness these atypical may avert unnecessary HighlightIgG4-RD inflammatory pseudo-tumors mass.It essential mass, so surgery prevented.