Objective:

To highlight the diagnostic challenge of IgG4-related autoimmune pancreatitis (IgG4-AIP) misdiagnosed as acute pancreatitis (AP) in a patient with type 2 diabetes mellitus (T2DM).

Approach:

• Case Presentation: A 60-year-old male with T2DM presented with blurred vision and lower limb numbness, later developing recurrent abdominal pain and elevated pancreatic enzymes.
• Diagnostic Process: Initial diagnosis was AP; however, persistent symptoms and elevated serum IgG4 led to reassessment and diagnosis of IgG4-AIP.

Key Findings:

• The patient had a markedly elevated serum IgG4 level of 13.8 g/L.
• Imaging findings were unremarkable for typical acute pancreatitis, with no evidence of a discrete pancreatic mass or significant ductal abnormalities.
• The patient showed improvement in symptoms and a decrease in serum IgG4 and pancreatic enzyme levels following glucocorticoid therapy.

Interpretation:

In patients with type 2 diabetes mellitus presenting with recurrent abdominal pain and elevated pancreatic enzymes that do not respond to treatment for acute pancreatitis, IgG4-related autoimmune pancreatitis should be considered as a potential diagnosis.

Limitations:

• The case is based on a single patient, which limits the generalizability of the findings.
• Atypical imaging findings may complicate the diagnosis and delay appropriate treatment.

Conclusion:

Timely measurement of serum IgG4 and careful integration of clinical, imaging, and histopathological data are crucial for early diagnosis of IgG4-AIP.