¹⁸F-FDG PET-CT usefulness in extra-pancreatic involvement in IgG4 related diseases.

IgG4-related diseases are a group of recently identified entities that include disorders that were previously known by other names, such as Mikulicz disease, Küttner's tumor, Riedel thyroiditis, among others, as well as some new ones described in the last years. These pathologies are a challenge for the medical community in terms of diagnosis and characterization due to their wide spectrum of clinical presentation. Functional imaging can provide a new approach to the comprehension of physiopathology, staging and targeting site of biopsy of IgG4-related diseases. In this clinical note, we describe five patients who underwent ¹⁸F-FDG PET-CT and correlate their findings with previous reports.