IgG4-Related Diseases-Continues To Be a Cancer Mimicker.

Immunoglobulin G4-related disease (IgG4-RD) is a chronic multisystem immune-mediated disease. Histologically, it presents as infiltration with IgG4-secreting plasma cells affecting many organs such as the pancreas, lacrimal glands, salivary glands, kidneys, and arteries, resulting in chronic fibrosis and scarring within the tissue which over time forms into a mass. It is a slow-growing process that usually remains indolent until it causes a mass effect or tissue infiltration.