Idiopathic sclerosing mesenteritis
Rare disease of small intestine mesentery with chronic inflammation.
Idiopathic sclerosing mesenteritis (ISM) is an uncommon condition affecting the small intestine, marked by long-term inflammation and later scarring of the mesentery. It is also known as mesenteric lipodystrophy or retractile mesenteritis. The diagnosis is confirmed through tissue analysis that reveals fat cell death, fibrous tissue buildup, and ongoing inflammation in the small intestine.
Many people with this disease have no symptoms or very mild ones, but chronic and severe abdominal pain is the most frequent complaint. Others experience ongoing bowel issues such as diarrhea, bloating, gas, and cramping that can range from mild to severe. On examination, the mesentery may show a single lump, though widespread thickening is more common.
Several possible causes have been proposed, including injury, past surgeries, autoimmune conditions like lupus, IgG4-related disease, and rheumatoid arthritis, infections such as tuberculosis, cryptococcosis, schistosomiasis, and HIV, and medications like paroxetine and pergolide. However, these links are mostly speculative and subject to significant bias.
For diagnosis, a CT scan can help assess the disease. A finding called "misty mesentery" describes increased fat density in the mesentery, but this is not specific and can appear in other conditions like swelling, lymphedema, bleeding, or the presence of cancer or inflammatory cells, which must be ruled out. Mesenteric lymph nodes in ISM are rarely larger than 10 mm; larger nodes require further testing with a PET scan or biopsy. An MRI may show intermediate T1 signal and variable T2 signal depending on the amount of swelling or scarring—more swelling gives a high T2 signal, while more scarring gives a low T2 signal.
The condition often mimics other abdominal diseases, such as pancreatic or widespread cancer, making CT scanning important for an initial diagnosis.
Treatment options include medications like corticosteroids, tamoxifen, and thalidomide.
ISM is extremely rare, with only about 300 patients diagnosed worldwide as of 2014, and it is likely underdiagnosed. It can occur in children.
A large study from the Mayo Clinic in Rochester included 92 patients with widely varying symptom severity. Most were male, with an average age of 65. Common symptoms included abdominal pain (70%), diarrhea (25%), and weight loss (23%).
- Field
- Gastroenterology / Pathology
- Known for
- Rare chronic inflammation and fibrosis of the mesentery
- Symptoms
- Abdominal pain, diarrhea, bloating, cramping
- Diagnosis
- CT scan showing 'misty mesentery'; MRI with variable T2 signal
- Treatment
- Corticosteroids, tamoxifen, thalidomide
- Estimated cases
- About 300 patients worldwide (as of 2014)
Lore & Background
Idiopathic sclerosing mesenteritis may present with no or nearly no signs or symptoms, but many people have chronic and severe pain in the abdomen as the most common chief complaint. Other people have chronic problems with bowel movements, resulting in diarrhea, bloating, gas, and cramping which can range from severe to mild. Examination of the mesentery may indicate a solitary mass, but diffuse mesentery thickening is common.
Several causes have been suggested such as trauma, prior surgical procedures, autoimmune diseases like lupus, IgG4-related disease, rheumatoid arthritis, infections such as tuberculosis, cryptococcosis, schistosomiasis, HIV and medicines such as paroxetine and pergolide, but their associations are largely speculative with high degree of bias. The Mayo Clinic in Rochester reported a large study of 92 patients, with widely ranging severity of their symptoms; the majority were male, with an average age of 65 years. They commonly had abdominal pain (70%), diarrhea (25%), and weight loss (23%).
Reader's Guide
Idiopathic sclerosing mesenteritis is significant as an extremely rare disorder that often mimics other abdominal diseases such as pancreatic or disseminated cancer, making CT scanning important for initial diagnosis. Its epidemiology is poorly understood, with only about 300 patients diagnosed worldwide as of 2014, and it is probably underdiagnosed. The condition can occur in children. Treatment options include corticosteroids, tamoxifen, and thalidomide, though evidence is limited. The Mayo Clinic case series of 92 patients found that 56% received only pharmacological therapy, most often tamoxifen with a reducing dose of prednisone, and that symptomatic patients benefited from medical therapy, though further follow-up information would strengthen these results. The disease can be debilitating although relatively benign.
Did You Know?
- Idiopathic sclerosing mesenteritis is also called mesenteric lipodystrophy or retractile mesenteritis.
- A CT scan finding of 'misty mesentery' is used to describe increased mesenteric fat density, but it is not specific to this disease.
- The Mayo Clinic study of 92 patients found that 70% had abdominal pain and 25% had diarrhea.
- Only about 300 patients worldwide had been diagnosed with the condition as of 2014.
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