|ECR 2019 / C-1111|
|The Spectrum of IgG4-Related Sclerosing Disease in the Abdomen|
IgG4-related disease (IgG4-RD) is a multisystemic and increasingly diagnosed immunemediated fibroinflammatory condition characterized by diffuse or focal tumor lesions with a dense lymphoplasmacytic infiltrate enriched in IgG4-positive plasma cells associated with obliterative phlebitis and a variable degree of fibrosis. Elevated IgG4 serum levels are found in 60-70% of patients, but they are not pathogenic and only represent a down-regulatory response of the immune system.
IgG4-RD mostly affects men older than 50 years-old. The disease is also increasingly recognized to occur in children. It can synchronously or sequentially involve virtually all the organ systems of the abdomen, being the most common the pancreas, but it can also affect the biliary tree and gallbladder, retroperitoneum, kidney, prostate and lymph nodes.
It is usually a self-limiting condition, but if vital organs are involved, aggressive treatment with glucocorticoids is mandatory since it can lead to serious organ failure. Treatment is effective in the majority of patients, but disease flares are common, so azathioprine, mycophenolate mofetil, and methotrexate are used frequently as glucocorticoid-sparing agents or remission-maintenance drugs.
CT, MR and 18F-FDG PET-CT are the imaging modalities of choice to depict characteristic imaging features and extent of IgG4-RD. Both morphologic and functional imaging are complimentary for evaluation of response to therapy.