Final answer:
Retroperitoneal fibrosis can lead to complications such as IgG4 related diseases, autoimmune cholecystitis, autoimmune pancreatitis, and Reidel's thyroiditis.
Step-by-step explanation:
Retroperitoneal fibrosis is a condition characterized by the fibrotic thickening of tissues in the retroperitoneal space. Some complications associated with retroperitoneal fibrosis include IgG4 related diseases, autoimmune cholecystitis, autoimmune pancreatitis, and Reidel's thyroiditis. These complications can arise due to the inflammation and scarring caused by the fibrosis, leading to dysfunction of the affected organs.