IDIOPATHIC MESENTERIC PANNICULITIS

M. LIMEME, H. ZAGHOUANI BEN ALAYA, H. AMARA, D. BEKIR, CH. KRAIEM

Imaging department, Farhat Hached Hospital, Sousse, Tunisia

GI26

Introduction

• Synonyms:

retractile mesenteritis, fibrosing mesenteritis,

mesenteric panniculitis, mesenteric lipodystrophy,

liposclerotic mesenteritis, systemic nodular

panniculitis.

• Definitions:

Complex mesenteric inflammatory disorder of

unknown etiology

Objectives

To describe the imaging features of non-specific inflammation of mesenteric fat tissue without associated pathology

and to formulate differential diagnosis.

Materials and Methods

• Among two men and a women (mean age 45 years), 2 were paifull,

• Diarrhea was noted in two cases,

• And fever in one case.

• An abdominal mass was found in two cases, • 3 patients had an inflammatory syndrome.

Results

• The diagnosis was suggested by computed tomography (CT): (single mass: 2 cases, diffuse mesenteric thickening: 1 case) and confirmed by pathology.

• Two patients were treated with corticosteroids. During the follow-up (mean 56 months) the panniculitis was stable on CT in 2 cases and regressed in one case.

• No associated pathology has emerged.

Abdominal pain and diarrheaCT findings: fat ring sign (arrowheads) and tumoral pseudocapsule (arrow).

Abdominal pain and diarrheaCT findings: Solid soft tissu mass in the root of small bowel mesenteryecasing mesenteric vessels.

Abdominal mass and feverCT findings: extensive infiltration of small bowel mesentery ecasing mesenteric vessels.

Discussion

Clinical issues

• Symptoms:

Abdominal pain, fever, nausea, vomiting, weight

loss, diarrhea.

Palpable mass.

Incidental finding in an asymptomatic patient.

Findings vary depending on predominant tissue• Area of subtle increesed attenuation in mesentery(inflamed fat): solitary/multiple; well/ill defined• Calcification, enlarged mesenteric lymph nodes,• Fatty necrotic cystic mass may be seen,• Infiltration of pancreas or portahepatis,• Encasement of mesenteric vessels and collateral

vessels: narrowing/occlusion on contrast study

CT findings

Increesed attenuation in mesentery (red arrow) with well defined outlines: pseudocapsule.Encasement of mesenteric vessels and collateral vessels (blue arrow)

• « Fat ring » sign: preservation of fat arround vessels:

- Hypodense fatty halo surrounding mesenteric vessels and nodules,

- Predominantly seen in mesenteric panniculitis,- Differentiates scleroing mesenteritis from other

mesenteric processes (lymphoma, carcinoid tumor, carcinomatosis)

CT findings

« Fat ring » sign: preservation of fat arround vessels

Horton and al. Radiographics. 2003 ;23(6):1561-7

• Pseudocapsule: peripheral band of soft tissue attenuation that limits normal mesentery from inflammatory process:

- Seen in mesenteric panniculitis phase,- Enhancement of pseudocapsule may be seen.• Thickening/infiltration/displacement/narrowing

of bowel loops.

CT findings

Pseudocapsule: peripheral band of soft tissue attenuation that limits normal mesentery from inflammatory process

• « Misty mesentery »: nonspecific sign- Increesed attenuation of mesentery,- Evidence of small mesenteric nodes,- No discret soft tissu mass,- Seen in any pathology that infiltrates mesentery

CT findings

• Solid soft tissu mass usually in root of small bowel mesentery (fibroous tissue)

- Single/large/lobulated/ill-defined increesed density mass with linear radiating strands (fibroma-rare)

- Small mesenteric soft tissue nodules of increesed density (fibromatosis)

CT findings

• Variable signal intensity due to: inflammation, fat, fibrosis, vascular and Ca++.

• Mesenteric panniculitis and lipodystrophy:- T1WI: mixed signal intensity,- T2WI: mixed signal intensity.• Retractile mesenteritis: in mature fibrotic reaction- T1WI: decreesed signal intensity,- T2WI: very low signal intensity,- Gradient-écho MR image:*Narrowing/occlusion of flow in mesenteric vessels*Collateral vessels are seen

MRI findings

• Non-Hodgkin lymphoma,• Carcinoid tumor,• Mesenteric edema,• Desmoid tumor (Fibromatosis),• Carcinomatosis (mesenteric metastasis)

Differential diagnosis

Differential diagnosis

Non-Hodgkin lymphoma

Differential diagnosis

Carcinoid tumor

Differential diagnosis

Mesenteric edema

Differential diagnosis

Desmoid tumor

Differential diagnosis

Carcinomatosis (mesenteric metastasis)

• Steroids, colchicine, immunosuppressive agents: before fibrotic changes.

• Surgical excision: fibrosis and retraction with obstructive symptoms.

Treatment

Conclusion

• Various diseases (usually malignant) can mimic the imaging features or be associated.

• Pathological verification leads to affirm the idiopathic mesenteric panniculitis, a benign entity of unknown pathogenesis.

• Corticosteroid therapy is reserved for symptomatic patients.