Long-term imaging characteristics of the pancreas related to diabetes induced by immune checkpoint inhibitor therapy

BACKGROUND: Immune checkpoint inhibitor (ICI)-induced diabetes is a rare endocrine immune-related adverse event, and long-term pancreatic magnetic resonance imaging (MRI) findings after disease onset have not been well characterized. CASE PRESENTATION: An individual developed abrupt hyperglycemia during pembrolizumab therapy for recurrent renal cell carcinoma and subsequently required insulin therapy. Serum C-peptide rapidly declined to below the detection threshold, whereas pancreatic enzyme levels remained within normal limits throughout follow-up. MRI performed 1 day after diagnosis demonstrated diffuse high signal intensity on diffusion-weighted imaging (DWI) and reduced apparent diffusion coefficient (ADC) values throughout the pancreas. Serial imaging over 25 months showed progressive pancreatic atrophy, whereas the DWI/ADC features persisted. CONCLUSION: This case provides a new descriptive longitudinal radiological observation of persistent diffusion-related pancreatic MRI findings and progressive pancreatic atrophy after the onset of ICI-induced diabetes.