1. Mesenteric panniculitis
BEN ROMDHANE MH
Hopital AVICENNE BOBIGNY

2. 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

3. 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

4. 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

5. 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

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

7. 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

8. 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 ...)

9. 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

10. 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

11. 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

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

13. 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

16. Piessen G Annales de chirurgie 131 2006

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

18. Fat-ring sign Fat-ring sign or “fatty halo 75–85%
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-Hodgkin’s lymphoma in which chemotherapy treatment has led to reduction of the mesenteric lymphadenopathy, leaving a fine haziness throughout the mesenteric fat

20. 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 50–59% 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

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

23. 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

24. 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

27. 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

28. Farzana Nawaz Ali, Case Reports in Medicine2010

29. Farzana Nawaz Ali, Case Reports in Medicine 2010

30. 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

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

34. 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

35. 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

37. 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

39. Neoplasm Non-Hodgkin’s 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 patient’s prior CT scans

40. 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

44. 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

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

46. 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

47. 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

48. 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

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

50. 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