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

Abstract

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