The Misty Mesentery Dilemna Kristin Greenlaw

PGY4 Dalhousie University

Objectives

Review the differential diagnosis of misty mesentery

finding on CT

Discuss Sclerosing Mesenteritis (SM): Etiology, Findings,

Differential

Follow up recommendations

Incidental finding, what to do…

Follow up or let it go?

Misty Mesentery

A regional increase in mesenteric fat density

May be caused by mesenteric infiltration of:

Inflammation

Neoplastic cells

Fluid (edema, blood, lymph)

Fibrous tissue/Idiopathic

Mindelzun et al., 1996

Fluid

Mesenteric edema

Heart failure

Portal hypertension

Cirrhosis

Lymphatic obstruction

Neoplasm

Trauma/Surgery

Radiation

Lymphatic malformation

Hemorrhage

Trauma

Anticoagulation

Ischemic enteritis

Imaging features

- Often associated with

generalized edema or ascites

- Additional retroperitoneal and

omental fluid

Inflammation

Underlying pancreatitis, appendicitis,

diverticulitis, and other “itis’”

TB

enlarged lymph nodes with central

hypodensity

nodular mesentery

enhancing smooth peritoneal thickening

high density ascites

Case

- Subtle mesenteric stranding, plus stranding

around the gallbladder

fossa

- US findings consistent

with cholecystitis

Neoplasm

Non Hodgkin Lymphoma

Carcinoid

Metastasis

Misty mesentery appearance may be caused by

tumour cell infiltration, or obstruction of lymphatics

Idiopathic – Sclerosing Mesenteritis

92% is incidental, 0.6% of all studies

Can be symptomatic – pain, nausea, fever, mass, obstruction

Reported association with future malignancy, up to 30%, but is this a true association?

Possible causes

Post surgery/trauma

Vasculitis

Infection

Autoimmune (IgG4 related condition)

Mesenteric Lipodystrophy

•Fat replaced by foamy macrophages

•Mesenteric stranding and mild lymphadenopathy

Mesenteric Panniculitis

•Infiltrate of plasma cells, PMNs, foamy macrophages

•Mesenteric stranding and mild lymphadenopathy

Retractile Mesenteritis

•Collagen, fat necrosis, fibrosis

•Mesenteric stranding +/- soft tissue mass, mild lymphadenopathy

Sclerosing

Mesenteritis

Sclerosing mesenteritis (SM) is an overarching term, including several other pathologic diagnoses depending on the appearance and stage of disease

Sclerosing Mesenteritis

Imaging Findings

Most often involves the jujenal mesentery

Oriented to the left

Fat ring sign – sparing of fat around vessels

Tumoral pseudocapsule - <3 mm thickness, surrounding stranding

Mesenteric root mass – can calcify, cause mass effect

However, all features are non-specific and can rarely be seen with neoplasm

Mesenteric lipodystrophy and mesenteric panniculitis can have a similar appearance on CT

Example of:

Pseudocapsule

Fat ring sign

Taffel et al., 2014

Retractile mesenteritis

An example of:

- Spiculated mesenteric

root mass

- Compression of

adjacent vessels

- Calcification

Taffel et al., 2014

Differentiating Sclerosing Mesenteritis

and Malignancy

Sclerosing mesenteritis

Compression/obstruction of structures

Pseudocapsule

Mildly enlarged lymph nodes

+/- Calcification

Carcinoid

Spiculated mass with mesenteric spread

Primary hyperenhancing small bowel mass

Hepatic metastasis

70% calcified

Lymphoma

Encasement of structures

Other lymph node groups enlarged

Nodular

If treated: infiltrative stranding, and calcification

Multiple imaging features of SM

However, lymph nodes >1 cm, and multiple mildly enlarged lymph nodes

in other areas (mediastinal, retroperitoneal)

6 Follow up CT suggested

Case 1 February 2014

Follow up CT did not occur until 1 year later

Large retroperitoneal mass of conglomerate lymph nodes, and further enlargement of other nodes

Pathology proven Diffuse Large B Cell Lymphoma

Case 1 February 2015

Case 2 Incidental mesenteric stranding and soft tissue nodules,

measuring > 1cm. Multiple imaging features of SM.

Case 2 The mesenteric findings were similar on a follow up CT,

however, a single enlarged retrocrural node is increased >1 cm.

Suspicious for lymphoma!

March 2014 July 2014

Follow up

Tallef et al., 2014 suggests:

Soft tissue nodule >10 mm, consider biopsy, or close CT

follow up

If no history of malignancy and lymph nodes smaller than 5

mm - no follow up

Corwin et al., 2012 found:

Followed patients with imaging diagnosis of sclerosing

mesenteritis for 2 years

0/30 developed lymphoma if lymph nodes <1 cm

3/7 developed lymphoma if lymph nodes >1 cm

Conclusions

Misty mesentery finding has a wide differential

Consider an inflammatory, traumatic or neoplastic

etiology before labeling as sclerosing mesenteritis

Suggested follow up

If isolated to mesentery and lymph nodes <5 mm, no follow

up required

If nodes 5-10 mm consider follow up (~6 months)

If nodes >10 mm consider surgical referral, biopsy or close

interval follow (3-6 months)

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