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 US-found 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 extra-mesenteric 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