Mesenteric panniculitis
BEN ROMDHANE MH
Hopital AVICENNE BOBIGNY
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
• 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
• 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
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
• MP occurs independently or in
association with other disorders
• A variety of possible causative factors
have been proposed:
autoimmune disorders
ischemia
prior abdominal surgery
• 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
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 ...)
• 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
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
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 USfound mesenteric abnormalities
A. C. van Breda Vriesman Eur Radiol (2004)
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
Piessen G Annales de chirurgie 131 2006
• Other CT features reported
• may be valuable clues for the diagnosis:
the fat-ring sign,
tumoral pseudocapsule
soft-tissue nodules
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
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
A. C. van Breda Vriesman Eur Radiol (2004)
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
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
• 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
Farzana Nawaz Ali, Case Reports in Medicine2010
Farzana Nawaz Ali, Case Reports in Medicine 2010
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
• imaging diagnosis can therefore be made
only after exclusion of any of the following
alternative causes of a misty mesentery
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
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
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
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
• 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
• 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 extramesenteric peritoneal nodules, or by
cytological analysis of ascites
A. C. van Breda Vriesman Eur Radiol (2004)
• 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
• 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
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
• Variable course With treatment:
relatively benign course
progression of the disease
eventually leads to death
In some cases, complete resorption
• 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