The mesentery is a fold of tissue within the peritoneum that supports and attaches the small and large intestines to the walls of the abdomen.
Mesenteric panniculitis is a rare disorder that is part of a spectrum of diseases that affect the mesentery , a portion of the peritoneum that supports and connects the intestines to the abdominal wall.
People with mesenteric panniculitis develop inflammation and necrosis of the fatty tissue of the mesentery, especially in the area of the small intestine. The condition progresses to cause chronic inflammation of the mesentery.
In some patients, ongoing inflammation can lead to scarring (fibrosis) of the mesentery.
The mesentery contains fat, blood vessels, lymphatic tissue, lymphatic vessels, and other forms of connective tissue. The peritoneum is a membrane that lines the abdominal cavity and covers the abdominal organs.
The mesentery of the small intestine is most commonly affected in mesenteric panniculitis.
Although the exact cause of mesenteric panniculitis remains unknown, the disease has been associated with a variety of other conditions, including neoplasms, other autoimmune diseases, and abdominal trauma.
This disease progresses in three stages:
- Mesenteric lipodystrophy : it is the first stage. A type of cell of the immune system replaces the fatty tissue in the mesentery.
- Mesenteric panniculitis: it is the second stage. Other types of cells of the immune system infiltrate the mesentery, and a great deal of inflammation occurs during this stage.
- Retractile mesenteritis: it is the third stage. It is when inflammation is accompanied by the formation of scar tissue in the mesentery.
Signs and symptoms
In general, mesenteric panniculitis is a chronic benign disorder with a favorable prognosis that sometimes resolves on its own (spontaneous regression).
However, the symptoms of mesenteric panniculitis can be severe in some patients and can have significant effects on quality of life.
The clinical presentation of mesenteric panniculitis is highly variable. Some patients have few or no noticeable symptoms.
The diagnosis of mesenteric panniculitis can be made incidentally after a CT scan of the abdomen, usually for evaluation of abdominal pain.
The symptoms of mesenteric panniculitis fall into two categories.
Some symptoms, such as abdominal pain, are due to the mass-like effect of mesenteric inflammation and the possible involvement of adjacent structures, including the small intestine.
The second group of symptoms occurs in the presence of chronic inflammation and can include:
Some affected people may develop complications such as small bowel obstruction or acute abdomen.
Small bowel obstruction prevents the passage of food through the intestines and can cause a variety of nonspecific gastrointestinal symptoms as well as nutrient malabsorption.
The most common symptom of mesenteric panniculitis is abdominal pain. The pain is usually localized in the middle portion of the abdomen, but can also be present in other areas of the abdomen or pelvis.
Other common symptoms include:
- Early satiety.
- Involuntary weight loss
- Altered bowel habits ( constipation or diarrhea).
- In some patients, a tender mass may be detected in the middle portion of the abdominal mass.
The abdominal distention of chylous ascites has also been described. A complete examination is necessary to rule out peripheral lymphadenopathy or other signs of neoplasia in patients.
Evidence from multiple studies suggests that mesenteric panniculitis is an autoimmune disorder.
Autoimmune diseases occur when the body’s natural defense mechanisms such as antibodies and lymphocytes (which are normally in place for the prevention of infectious diseases and cancer), instead cause a reaction and damage to the patient’s own healthy tissue.
In general, genetic and environmental factors play a role in the development of autoimmune diseases.
Several factors support the hypothesis that mesenteric panniculitis is an autoimmune disease. These include the fact that biopsies of the affected areas show chronic and ongoing inflammation.
Additionally, systemic symptoms that are characteristic of other autoimmune diseases such as rheumatoid arthritis and Crohn’s disease , including fever and fatigue, can occur in patients with mesenteric panniculitis.
Patients with mesenteric panniculitis also often have a strong family history of autoimmune diseases.
Finally, elevation of inflammatory markers that are measured in the blood, such as erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), are often found in patients with mesenteric panniculitis.
Because mesenteric panniculitis occurs in some patients after certain medications, infections, abdominal surgery, or trauma, other theories have been proposed to explain this disorder, including post-inflammatory reactions to acute inflammation or infection, or poor blood supply (ischemia ) to the mesentery.
However, these conditions probably develop as a consequence of an autoimmune reaction.
Elevated inflammatory markers that are measured in the blood, such as erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), are often found in patients with mesenteric panniculitis.
Unfortunately, a proportion of patients with mesenteric abnormalities consistent with mesenteric panniculitis on CT scan will have an underlying form of cancer (malignancy).
In a recent study, about 28% of patients with abnormal CT scan of the mesentery suggestive of mesenteric panniculitis had a known history of cancer or had recently been diagnosed with cancer.
The most common cancers with mesenteric panniculitis, as abnormalities on CT scan are lymphomas. Other cancers associated with this finding include carcinoid, colon, kidney, and prostate tumors.
Mesenteric thickening and inflammation may represent a paraneoplastic syndrome, defined as the presence of a cancer in the body that is causing an abnormality that is not due to the physical presence of cancerous tissue in the affected area.
There is also a known association between mesenteric panniculitis and other fibrosclerotic disorders. This suggests that mesenteric panniculitis belongs to a broader spectrum of diseases in which inflammation and fibrosis affect multiple organ systems in the body.
Fibrosclerotic disorders that have been reported to occur with mesenteric panniculitis include retroperitoneal fibrosis, Sjögren’s syndrome, and sclerosing pancreatitis.
The epidemiology of mesenteric panniculitis has not been fully defined.
A recent study reported that findings consistent with mesenteric panniculitis occurred in 359 patients (0.24%) of a total of 147,794 abdominal computed tomography (CT) examinations performed over 5 years in a large community medical system.
Of these, 100 patients (28%) had known malignancy or were later diagnosed with cancer. In some reports, mesenteric panniculitis has a male prevalence of 2: 1.
Mesenteric panniculitis appears most frequently during the sixth and seventh decades of life, and its incidence appears to increase with age.
Children and adolescents are affected less frequently, possibly due to less fat in the mesentery, but more importantly due to the specific characteristics of this form of autoimmunity.
The symptoms of mesenteric panniculitis are similar to those of other benign and malignant diseases. Because of this, it is important to rule out other diseases before confirming the diagnosis of mesenteric panniculitis.
Infectious causes range from viral, bacterial (including V. cholerae), and parasitic infections. There are also a variety of diseases that are associated with mesenteric abnormalities on abdominal images.
Such conditions include:
- Primary or metastatic mesentery cancer.
- Gastrointestinal lymphoma.
- Desmoid tumors.
- Inflammation of the pancreas (pancreatitis).
- Crohn’s disease .
- Idiopathic nodular paniculitis.
- Locally advanced pancreatic adenocarcinoma.
- Fibrosis retroperitoneal.
- Other sclerotic diseases as mentioned above.
The diagnosis of mesenteric panniculitis is based on the identification of suggestive symptoms, a detailed history of the patient, and a thorough clinical evaluation.
Clinical tests and treatment
Affected people may have non-specific laboratory abnormalities, such as low red blood cell counts (anemia).
Laboratory markers of inflammation such as erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) may also be elevated.
Radiographic studies such as computed tomography (CT) or magnetic resonance imaging (MRI) reveal characteristic findings in the abdominal or pelvic mesentery. Images reveal characteristic thickening, fat necrosis, and calcification of the mesentery.
Mild cases refer to a “hazy mesentery.” Enlargement and calcification of the pelvic and mesenteric lymph nodes are commonly present.
Because mesenteric panniculitis is not an invasive disorder, the blood vessels within the mesentery appear to be spared from the inflammatory mass.
A surgical biopsy and microscopic study of the affected tissue are required to completely rule out other conditions and confirm a diagnosis of mesenteric panniculitis.
Most treatment recommendations are based on case reports or small case series. The only prospective clinical study of a treatment for mesenteric panniculitis has been done with the drug thalidomide.
The goals of treatment for mesenteric panniculitis are to reduce mesenteric inflammation and control symptoms of the disease.
In general, people who do not have symptoms are not treated, but are regularly monitored to see if the disorder progresses on abdominal images (watch and wait).
A decision is made regarding the biopsy during this time. In most patients, the disease remains asymptomatic. The mesenteric mass is usually stable or even regresses on its own.
For patients with symptoms related to chronic mesenteric inflammation, anti-inflammatory agents, especially corticosteroids, are the initial treatment of choice.
Additional anti-inflammatory medications that have been used to treat mesenteric panniculitis include colchicine, azathioprine, cyclophosphamide, infliximab, and pentoxifylline.
A prospective clinical trial has shown that the drug thalidomide improves symptoms and reduces blood levels of ESR and CRP in patients with mesenteric panniculitis. Low-dose naltrexone (NDL) is also a promising new therapy for mesenteric panniculitis.
NDL appears to work by modulating the immune system and increasing blood levels of enkephalins and endorphins. Tamoxifen and other hormonal therapies have been proposed to treat patients with mesenteric fibrosis due to their antifibrotic effects.
Unfortunately, serious effects can occur with these drugs, including the development of thromboembolic phenomena and secondary neoplasms.
Due to the rarity of mesenteric panniculitis, it is likely that few controlled clinical trials of medical therapies for this condition will be conducted in the future.
When people with mesenteric panniculitis develop small bowel obstruction, surgery may be required. In general, surgery should be avoided in patients with mesenteric panniculitis and surgical removal of the mesenteric mass should never be attempted in order to cure the disease.