As you see, there are bilateral lesions in the kidneys and a retroperitoneal mass. Do you know any disease that features both? If you don't, maybe google does :)
IgG 4 related sclerosing disease includes pancreatitis, renal bilateral lesions and retroperitoneal fibrotic mass. There are also other sites of involvement and manifestations like biliary disease, sclerosing mesenteritis, lymphadenopathy, inflammatory bowel disease, head and neck disease, vascular disease and pulmonary involvement.
Significant improvement of the previously discussed radiological findings after treatment. The patient is still on medication and remains asymptomatic.