Mesenteric panniculitis

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Mesenteric panniculitis

• BEN ROMDHANE MH
• Hopital AVICENNE BOBIGNY

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Mesenteric panniculitis

• inflammatory disorder of the fatty tissue of the
  bowel mesentery
• Uncommon
• several names( resulting in considerable
  confusion )
• lipodystrophy,
• mesenteric Weber-Christian disease,
• fibrosing mesenteritis,
• sclerosing mesenteritis
• retractile mesenteritis

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• varied terminology reflects the pathological
  spectrum
• now considered to be one single disease
• chronic nonspecific inflammatory process in the
  mesentery
• rarely may lead to fibrosis and retraction
• If inflammation predominates over fibrosis
• the process is known as mesenteric
  panniculitis
• when fibrosis and retraction predominate, terms
  fibrosing mesenteritis, retractile mesenteritis
  or sclerosing mesenteritis are more commonly used
  

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• MP supposed to be very rare, approximately 250
  cases reported in the literature
• With increased use of abdominal diagnostic
  imaging, MP is diagnosed more often
• Recently reported prevalence of 0.6 of all
  patients undergoing an abdominal CT for various
  indications

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Pathogenesis

• infiltration of mesenteric fat by
• inflammatory cells, mainly lymphocytes
• and fat-laden macrophages
• with inflammation, a mixture of fat necrosis and
  fibrosis may be present in the mesentery
• exact cause remains unclear

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• MP occurs independently or in association with
  other disorders
• A variety of possible causative factors have been
  proposed
• autoimmune disorders
• ischemia
• prior abdominal surgery

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• also suggested paraneoplastic response
• This possible association with a concomitant
  malignancy highlighted in a study by
  Daskalogiannaki
• reporting the presence of a coexisting abdominal
  or distal malignancy in 69 of patients with CT
  features of MP
• In other studies prevalence of malignancy not
  different from general population of patients
  undergoing CT for all various indications

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Clinical characteristics

• mostly middle or late adulthood,
• male predominance.
• Clinical manifestations may be related to the
  inflammation or to mass-effect
• Presenting symptoms may vary
• may also be entirely asymptomatic
• commonly include non-specific abdominal pain
• Palpable abdominal mass may be present may lead
  to the clinical misdiagnosis (aortic aneurysm
  ...)

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• Laboratory findings often within the normal
  range or demonstrate non-specific findings
• mild leucocytosis and elevation of the
  erythocyte sedimentation rate.
• before the advent of modern diagnostic imaging,
  MP was diagnosed exclusively as an unexpected
  finding at exploratory laparotomy or autopsy

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Diagnosis

• A definite diagnosis of MP can be made only by
  pathologic analysis
• However, the incidental benign and often
  asymptomatic nature of MP usually does not
  justify biopsy
• In these cases, diagnosis may be suggested by
  characteristic imaging features from the
  radiological literature from pathologically
  proven cases

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US features

• often quite subtle may be easily overlooked
• poorly defined hyperechoic change of the
  mesenteric fat
• decrease in mesenteric compressibility
• may be seen in various conditions with
  mesenteric involvement( lipomatous tumors...
• CT always recommended to analyze any US-found
  mesenteric abnormalities

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• A. C. van Breda Vriesman Eur Radiol (2004)

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CT features

• increased density of mesenteric fatty tissue
  (approximately- 40 to -60 HU) compared to the
  attenuation values of normal retroperitoneal or
  subcutaneous fat
• (-100 to -160 HU)
• hyperattenuating fat surrounds mesenteric vessels
• but does not displace them
• some regional mass-effect by displacing locally
  small bowel loops
• mass most frequently located at the left side
• corresponding to jejunal mesentery

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• Piessen G Annales de chirurgie 131 2006

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• Other CT features reported
• may be valuable clues for the diagnosis
• the fat-ring sign,
• tumoral pseudocapsule
• soft-tissue nodules

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Fat-ring sign

• Fat-ring sign or fatty halo 7585
• low-density fat surrounding vessels and nodules
• preservation of normal fat density, corresponding
  to unaffected noninflamed fat interposed between
  vessels or nodules and inflammatory cells at
  histopathology
• non-specific
• also reported incidentally in non-Hodgkins
  lymphoma in which chemotherapy treatment has led
  to reduction of the mesenteric lymphadenopathy,
  leaving a fine haziness throughout the mesenteric
  fat

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Tumoral pseudocapsule

• peripheral band with soft-tissue attenuation
  limiting the inflammatory mesenteric mass
• thickness of this dense stripe usually does not
  exceed 3 mm
• reported in 5059 of patients
• lipomatous tumor (lipoma or liposarcoma) may be
  well-defined by a similar dense rim
• but these lesions will often show some
  mass-effect on the mesenteric vessels in contrast
  to M P

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• A. C. van Breda Vriesman Eur Radiol (2004)

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Soft-tissue nodules

• small soft-tissue nodules scattered within the
  hyperattenuating mesenteric mass
• in 80 of cases
• Correspond probably to lymph nodes
• usually less than 5 mm in diameter
• Mesenteric lymph nodes larger than 10 mm atypical
  for MP
• biopsy or fine-needle aspiration must be
  considered to exclude malignancy

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SM

• most commonly appears as a soft-tissue mass in
  the small bowel mesentery
• The mass may envelop the mesenteric vessels, and
  collateral vessels
• Mesenteric thickening and fibrosis
• often with nodular masses involving the
  appendices epiploicae of the colon

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• Calcification may be present, usually in the
• central necrotic portion of the mass
• it may be related to the fat necrosis
• Cystic components also described
• may be the result of lymphatic or venous
  obstruction and necrotic change
• Enlarged mesenteric or retroperitoneal lymph
  nodes may be present

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• Farzana Nawaz Ali, Case Reports in Medicine2010

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• Farzana Nawaz Ali, Case Reports in Medicine 2010

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Imaging-based differential diagnosis

• misty mesentery Alteration in the density of the
  mesenteric fat on CT
• with an extensive differential diagnosis
• MP reserved for idiopathic inflammation leading
  to a misty mesentery

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• imaging diagnosis can therefore be made only
  after exclusion of any of the following
  alternative causes of a misty mesentery

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Mesenteric edema

• Many causes
• heart failure, portal hypertension, mesenteric
  vascular thrombosis and lymphedema.
• mesenteric edema secondary to a systemic disease,
  usually associated with generalized subcutaneous
  edema and ascites.
• Ascites is not a feature of MP and indicates an
  alternative diagnosis

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Inflammation

• acute pancreatitis is the typical inflammatory
  process associated with increased CT density of
  the mesenteric fat
• usually centered in the peripancreatic region
• With usually increased levels of amylase in
  serum and urine enabling the diagnosis
• Focal inflammations such as appendicitis and
  colonic diverticulitis may also cause local
  hyperattenuation of adjacent mesenteric fat
• these diagnoses must be carefully ruled out

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Mesenteric Hemorrhage

• hemorrhage, caused by blood dissecting from
  mesenteric vessels or from the bowel wall
• may be traumatic or spontaneous
• A history of trauma, use of anticoagulantia
• or high-density peritoneal fluid suggests the
  correct diagnosis

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Neoplasm

• Non-Hodgkins lymphoma most common mesentery
  tumor
• Typically bulky lymphadenopathy,
• often also n the retroperitoneum, indicating the
  correct diagnosis
• Shrinkage of mesenteric lymphadenopathy after
  chemotherapy may result in residual scarring that
  may mimic MP
• Needs reviewing the patients prior CT scans

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• lymphoma manifested as nodal mass in the root of
  the mesentery may mimic SM
• no calcification unless previously treated
• Both can encase mesenteric vasculature
• lymphoma almost never result in ischemia
• fat halo sign favors a diagnosis of SM
• large, nodes favor lymphoma
• Treated lymphoma may also produce a misty
  mesentery simulating the MP

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• Primary mesenteric neoplasms (desmoid, mesenteric
  cyst, lipomatous tumors) cause mass-effect on
  mesenteric vessels
• Other tumors mesothelioma, or metastatic
  tumors( pancreatic, colon or ovarian carcinoma
  ) may affect the mesentery by soft-tissue tumor
  deposits, or may cause mesenteric edema by
  lymphatic obstruction
• correct diagnosis made by identification of the
  primary tumor or detection of extra-mesenteric
  peritoneal nodules, or by cytological analysis of
  ascites

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• A. C. van Breda Vriesman Eur Radiol (2004)

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• Carcinoid tumor may simulate SM
• ill-defined, infiltrating soft-tissue mass in
  the root of the mesentery with calcification and
  desmoplastic reaction
• fat ring sign favors a diagnosis of SM
• enhancing mass in bowel wall or hypervascular
  liver metastases
• sign diagnosis of carcinoid tumor

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• primary mesenteric mesothelioma can produce
  mesenteric soft-tissue implants
• in mesentery, also seen in the omentum and
  along the bowel surfaces.
• Ascites not associated with SM
• Calcification not common

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Treatment

• Treatment usually empirical
• may consist of steroids, colchicine,
  immunosuppressive agents, or orally administered
  progesterone
• In SM Surgical resection difficult
• due to vessel compromise
• may be of no clear benefit
• colostomy may be necessary
• with colonic involvement by SM

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• Variable course With treatment
• relatively benign course
• progression of the disease
• eventually leads to death
• In some cases, complete resorption

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• CT suggest the diagnosis of SM
• CT useful in distinguishing SM from other
  mesenteric diseases such as lymphoma or carcinoid
  tumor
• Biopsy necessary for SM diagnosis
• CT optimal study for the follow up