sclerosing mesenteritis

Sclerosing mesenteritis, also referred to as mesenteric panniculitis or retractile mesenteritis​, is an uncommon idiopathic disorder characterized by chronic non-specific inflammation involving the adipose tissue of the bowel mesentery.

Epidemiology  

Typically this condition afflicts adults in their sixties with mild male predilection, although reports vary .

Clinical presentation

Clinical presentation can be variable with abdominal pain, intestinal obstruction or ischemia, a mass, or diarrhea. Altered bowel habits, and weight loss may be present in some cases. Occasionally, intermittent partial bowel obstruction is encountered . A firm left upper quadrant / central abdominal mass may be felt . In some situations sclerosing mesenteritis is asymptomatic.

Pathology

The small bowel mesentery is affected in most cases although the sigmoid mesocolon and omentum can also occasionally be involved.

The disease is said to pass through three stages, although some authors believe these to be separate entities :

  • mesenteric lipodystrophy: degeneration of mesenteric fat
  • mesenteric panniculitis: inflammatory reaction
  • retractile mesenteritis / sclerosing mesenteritis: fibrosis, which may be associated with distortion or lymphatic obstruction
  • Macroscopic appearance

    Macroscopically, the mesentery is thickened with either solitary or multiple focal masses .

    Histology

    Histology demonstrates :

  • lipid-laden macrophages (mesenteric lipodystrophy)
  • lymphocytic aggregates and lymphoid follicles (mesenteric panniculitis)
  • variable amounts of fibrosis (retractile mesenteritis)
  • Associations

    Numerous associated conditions have been variably described including :

    There is debate about the association between systemic inflammatory conditions and mesenteric panniculitis. Determining causation is difficult. The term "secondary mesenteric panniculitis" is reserved by some authors for patients with systemic inflammatory conditions. Most authors would not use the term when there is a local cause for mesenteric inflammation.

      Radiographic features

      Ultrasound

      Ultrasound typically demonstrates distortion and thickening of the root of the mesentery with a slight decrease in echogenicity. Mass effect may be evident . A halo of sparing around vessels may be also seen on ultrasound as a region of hyperechoic fat . Color Doppler interrogation may show non-deviated mesenteric vessels within the mass .

      CT

      CT features are somewhat dependent on the main tissue component and include:

      • well-demarcated or ill-defined mesenteric mass-like lesion with surrounding "misty" attenuation
      • "misty" soft-tissue attenuation

      The mesentery demonstrates mass effect and may have a ground glass opacity (misty mesentery). Typically the traversing mesenteric vessels and soft tissue nodules have a spared fat halo (this has sometimes been referred to as the fat ring sign). Its orientation is aligned with the root of the jejunal mesentery. Punctate/coarse calcifications (~20%), as well as small lymph nodes (usually <5 mm), may be present within the region.

      MRI

      Findings are similar to CT. One report described a fibrous capsule around the inflammation .

      Nuclear medicine
      FDG PET-CT

      May have high accuracy for the differentiation between

      • sclerosing mesenteritis (or one of its stages): not FDG-avid
      • malignant mesenteric involvement: FDG-avid

      especially in patients with lymphoma . If in doubt, biopsy may be indicated in selected patients, even in asymptomatic lesions .

      Treatment and prognosis

      The mainstay of treatment is supportive, as the disease is typically self-limiting. If severe or protracted medical therapy with corticosteroids, cyclophosphamide or azathioprine can be contemplated . Mesenteric panniculitis cannot be completely resected and surgery is of no benefit. In up to 15% of cases, local lymphoma eventually develops . Some authors suggest associated malignancy rate of approximately 56% .

      History and etymology

      It was first described by Jura in 1924 as “retractile mesenteritis” and further labeled as “mesenteric panniculitis” by Odgen later in the 1960s.

      Differential diagnosis

      General imaging differential considerations include: