Retroperitoneal fibrosis: Year of the Zebra

Retroperitoneal fibrosis is a chronic inflammatory disorder where fibrous, scar-like tissue develops in the retroperitoneal area.

The peritoneum is the serous membrane that lines the abdominal cavity and covers the abdominal organs. The growth of fibrous tissue in the retroperitoneal space, or the space behind the peritoneum, leads to compression of the structures in that area, such as blood vessels like the inferior vena cava, and the ureters, which are the fibromuscular tubes that carry urine from the kidneys into the urinary bladder.

Initially, retroperitoneal fibrosis may be asymptomatic or cause nonspecific symptoms, like lack of energy, loss of appetite, unexplained weight loss, and low-grade fever.

As the disease progresses, the most common symptom is dull, low back or flank pain. In some cases, a palpable mass may be found in the abdomen or rectum.

External compression of the ureters may obstruct the normal flow of urine, resulting in the back-up of urine into the kidneys, which can result in kidney damage over time.

Compression of the inferior vena cava may result in swelling of the lower limbs and deep vein thrombosis, whereas compression of the retroperitoneal gonad vessels may lead to testicular pain and swelling.

Often, retroperitoneal fibrosis is discovered incidentally on a CT scan or other imaging techniques, which reveal a fibrous mass in the retroperitoneal space.

There are no specific laboratory tests for retroperitoneal fibrosis, but most individuals present elevated inflammatory markers and low blood cell counts, or anemia, due to chronic inflammation.

In cases where the diagnosis is not clear, a tissue biopsy may be done to distinguish between retroperitoneal fibrosis and other underlying conditions, such as an infection or malignancy.

Alright, now treatment of retroperitoneal fibrosis typically involves immunosuppressive therapy with corticosteroids and other medications, like methotrexate, azathioprine, or cyclosporine.

In cases of ureteral entrapment, surgery is typically done to free the ureters from the surrounding tissue and restore normal urine flow.

If surgery cannot be done, a stent can be placed into the ureter to allow for flow of urine. It is important to know that retroperitoneal fibrosis may recur months or years after surgery or steroid therapy, so serial imaging and monitoring is recommended to detect recurrences.

##SummaryAlright, as a quick recap, retroperitoneal fibrosis is caused by the development of fibrous, scar-like tissue behind the peritoneum, causing compression of the ureters and other retroperitoneal structures.

The most common complication is obstruction of the ureters, which may cause permanent kidney damage. Treatment generally involves surgery to free the entrapped organs and immunosuppression therapy to prevent progression of the disease.