Organ affected: Retroperitoneal

When IgG4-RD affects the retroperitoneum: hidden inflammation, varied symptoms, challenging diagnosis

IgG4-related disease (IgG4-RD) can affect many parts of the body. In this chapter, we’ll focus on retroperitoneal fibrosis, often shortened to RPF. The retroperitoneum is a deep space in the back part of the abdomen. Important structures reside or pass through this area, including:

• the kidneys

• the ureters – the structures that carry urine from the kidneys to the bladder

• the abdominal aorta (the largest artery in the body)

• the inferior vena cava (the largest vein in the body)

• portions of the pancreas

• nerves

In IgG4-RD, inflammation can lead to fibrosis, or scar-like tissue, in this space. This inflammatory scar tissue can wrap around nearby structures. If it presses on a ureter, blockage of the ureter can occur, a condition known as “hydronephrosis." 

In hydronephrosis, urine is unable to pass from the kidney to the bladder and backs up into the kidney, potentially causing serious kidney injury. If the inflammatory tissue compresses blood vessels (such as large veins), blood flow may be affected, leading to leg swelling, clots, or pain with walking.

RPF can be quiet at first. Some people have no symptoms, while others notice back, side, abdominal, or groin pain, changes in urination, leg swelling, fatigue, or weight loss. Because these symptoms overlap with many other conditions, RPF can be hard to recognize.

This chapter will explain how IgG4-RD can affect this internal space, why symptoms may be sneaky, and how diagnosis, treatment, and monitoring decisions are made.

IgG4-RD and retroperitoneal fibrosis
In this short video clip, Dr. Stuart Wiber explains where the retroperitoneal space is and how IgG4-RD can affect the ureters, kidneys, aorta, vena cava, and nearby tissues.