Autoimmune pancreatitis (AIP) is an uncommon inflammatory condition that can mimic pancreatic malignancy both clinically and radiologically, leading to diagnostic uncertainty. Two subtypes exist: Type 1 is linked to systemic IgG4-related disease, and Type 2 is confined to the pancreas. A 64-year-old woman was found to have submandibular and cervical lymphadenopathy during a routine physical examination. Further imaging revealed FDG-avid lymph nodes and pancreatic abnormalities, raising concern for malignancy. However, biopsy results confirmed Type 1 autoimmune pancreatitis (AIP) and IgG4-related sialadenitis. The patient was treated with corticosteroids, which resolved her symptoms and improved imaging findings. This case emphasizes the need to consider atypical presentations of AIP and highlights the effectiveness of steroid therapy in IgG4-related diseases.