What is mesenteric pannicolitis?

Mesenteric Panniculitis

Mesenteric panniculitis is a rare benign inflammatory disorder characterized by chronic inflammation and fibrosis of the adipose tissue primarily affecting the small bowel mesentery, which can lead to significant morbidity in symptomatic cases. Treatment should focus on symptom management with corticosteroids as first-line therapy for symptomatic patients, while asymptomatic cases generally require only observation as the condition may resolve spontaneously. 1

Definition and Pathophysiology

Mesenteric panniculitis (MP) is a benign fibroinflammatory process affecting the mesenteric adipose tissue, characterized by:

• Fat necrosis
• Chronic inflammation
• Fibrosis in the mesentery (primarily small bowel mesentery)

The exact etiology remains unknown, though associations with various conditions have been reported, including:

• Autoimmune disorders (e.g., Sjögren's syndrome) 2
• Malignancies (particularly lymphomas)
• Chronic inflammatory conditions
• Previous abdominal surgery

Clinical Presentation

MP can present with variable symptoms, with approximately 30-50% of cases being asymptomatic and discovered incidentally on imaging 3. When symptomatic, patients may experience:

• Abdominal pain (most common symptom)
• Bloating/abdominal distention
• Altered bowel habits (diarrhea or constipation)
• Nausea and vomiting
• Weight loss
• Fever and malaise
• In severe cases, intestinal obstruction requiring emergency intervention 4

Diagnostic Approach

The diagnosis of MP is primarily based on imaging findings, with confirmation often requiring histopathological examination:

1. Computed Tomography (CT): The primary imaging modality showing:

   • Mass-like area of increased fat attenuation within small bowel mesentery
   • Typically located in the left upper quadrant
   • Encasement of mesenteric vessels
   • Displacement of adjacent bowel segments
   • Presence of lymph nodes within the affected area 1

2. Positron Emission Tomography/CT (PET/CT):

   • May be performed to rule out underlying malignancy, particularly lymphoma 1

3. Histopathological confirmation:

   • Often requires surgical or percutaneous biopsy
   • Essential to exclude malignancy or infection 3

Differential Diagnosis

Important conditions to consider in the differential diagnosis include:

• Lymphoma
• Mesenteric carcinomatosis
• Carcinoid tumors
• Mesenteric fibromatosis
• Mesenteric edema from other causes (e.g., heart failure, hypoalbuminemia)

Treatment Approach

Treatment should be guided by symptom severity and presence of complications:

1. Asymptomatic patients:

   • Observation is recommended as MP may resolve spontaneously 3

2. Symptomatic patients:

   • First-line medical treatment: Prednisone and tamoxifen 1
   • Alternative options include other immunosuppressive or anti-inflammatory agents for refractory cases

3. Complications requiring surgical intervention:

   • Surgery should be reserved for cases with:
     • Recurrent bowel obstruction
     • Intestinal ischemia
     • When malignancy cannot be excluded 4
   • Surgical approach typically involves:
     • Intestinal bypass procedures
     • Segmental resection when necessary
     • Complete excision is often not feasible 3

Prognosis

The clinical course of mesenteric panniculitis is generally favorable:

• Most cases have an uneventful clinical course
• Spontaneous resolution occurs in many patients
• Long-term follow-up may be necessary to monitor for potential development of associated conditions

Clinical Pitfalls and Considerations

1. Misdiagnosis: MP can mimic malignancy, particularly lymphoma, leading to unnecessary aggressive interventions.

2. Overtreatment: Given its often benign and self-limiting nature, aggressive treatment should be avoided in asymptomatic patients.

3. Underdiagnosis: MP may be underdiagnosed due to its nonspecific symptoms and incidental nature on imaging.

4. Associated conditions: Always consider and evaluate for potential underlying conditions, particularly autoimmune disorders and malignancies.

5. Emergency presentations: Though rare, MP can present as acute abdomen requiring emergency surgery, as seen in cases with intestinal obstruction or ischemia 4.