E5239. Rays of Revelation: Unveiling Radiological Footprints of IgG4 Related Disease
  1. Meghana Kancharla; No Affiliation
  2. Aishwarya Gadwal; No Affiliation
  3. Shreyas Reddy K; No Affiliation
Immunoglobulin G4-related disease (IgG4-RD) is a multiorgan, complex immune-mediated disease that presents major diagnostic challenges. It is characterized by IgG4-positive plasma cell infiltration that causes inflammatory lesions and fibrosis. IgG4 RD is an uncommon mimic of various neoplastic and inflammatory etiologies.

Educational Goals / Teaching Points
Our objective is to exhibit both common and uncommon clinical and imaging presentations in IgG4 RD with pathological correlation in this case-based review.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Pancreas and biliary tract: the biliary tree and pancreas are the organs that are most frequently affected by IgG4-RD. On CT or MRI, IgG4-related autoimmune pancreatitis frequently manifests as a pancreatic mass or diffuse enlargement with a distinctive sausage-shaped appearance. Salivary and lacrimal glands: imaging of the salivary and lacrimal glands reveals bilateral symmetrical enlargement with homogenous enhancement on CT. CNS: infundibulohypophysitis, pachymeningitis, inflammatory orbital pseudotumor, and chronic subdural hemorrhage are the CNS manifestations of IgG4-RD. Lymph nodes: IgG4-RD can present as lymphadenopathy presenting as rounded, well-defined masses with homogeneous enhancement on CT and MRI, often mimicking lymphoma. Kidneys: various patterns of involvement are seen on imaging; focal lesions, diffuse involvement, perirenal soft tissue, renal sinus nodules, and pelvicalyceal thickening. Retroperitoneum: IgG4-related retroperitoneal fibrosis manifests as a soft-tissue mass that encases the ureters or covers the abdominal aorta and its branches, resulting in hydronephrosis and hydroureter. Other organs: IgG4-RD can affect virtually any organ, with imaging revealing characteristic features depending on the site. This includes mediastinal fibrosis, lung disease, breast involvement, and vascular disease.

A variety of imaging findings in various organ systems are present in IgG4-RD. The ability to distinguish IgG4-RD from other disorders and determine the most appropriate line of treatment depends on understanding these distinctive radiological findings.