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

 Hemorrhage

 Heart failure

 Trauma

 Portal hypertension

 Anticoagulation

 Cirrhosis

 Ischemic enteritis

 Lymphatic obstruction  Neoplasm  Trauma/Surgery  Radiation

 Lymphatic malformation

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

Sclerosing Mesenteritis

•Fat replaced by foamy macrophages •Mesenteric stranding and mild lymphadenopathy

Mesenteric Panniculitis

Retractile Mesenteritis

•Infiltrate of plasma cells, PMNs, foamy macrophages •Mesenteric stranding and mild lymphadenopathy

•Collagen, fat necrosis, fibrosis •Mesenteric stranding +/soft tissue mass, mild lymphadenopathy

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 - 1 cm, and multiple mildly enlarged lymph nodes in other areas (mediastinal, retroperitoneal)  6 Follow up CT suggested

 Follow up CT did not occur until 1 year later

Case 1

February 2015

 Large retroperitoneal mass of conglomerate lymph nodes, and further enlargement of other nodes  Pathology proven Diffuse Large B Cell Lymphoma

Case 2 Incidental mesenteric stranding and soft tissue nodules, measuring > 1cm. Multiple imaging features of SM.

March 2014

July 2014

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!

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

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 10 mm consider surgical referral, biopsy or close interval follow (3-6 months)

References 1. Al Zahrani, H., Kyoung Kim, T., Khalili, K., Vlachou, P., Yu, H., & Jang, H.-J. (2014). IgG4-related disease in the abdomen: a great mimicker. Seminars in Ultrasound, CT, and MR, 35(3), 240–54. 2. Brooke, R., Mindelzun, R. E., Lane, J., & Silverman, P. M. (1996). The Misty Mesentry on CT : Differential Diagnosis, (July), 61–65. 3. Carruthers, M. N., Stone, J. H., & Khosroshahi, A. (2012). The latest on IgG4-RD: a rapidly emerging disease. Current Opinion in Rheumatology, 24(1), 60–9. 4. Chen, T. S., & Montgomery, E. a. (2008). Are tumefactive lesions classified as sclerosing mesenteritis a subset of IgG4related sclerosing disorders? Journal of Clinical Pathology, 61(10), 1093–7. 5. Chopra, S., Dodd, G., Kedar, C., Esola, C., Ghiastas, G. (1999). Mesenteral, Omental and Retroperitoneal Edema in Cirrhosis: FIndings and Spctrum of CT Findings. Radiology. 211: 737-742. Dashkalogiannaki, Voloudaki, A., Prassopoulos, P., Magkanas, E., Apostolaki, E., & Gourtsoyiannis, N. (2000). CT Evaluation of Mesenteric Panniculitis : Prevalence and Associated Diseases, (February), 427–431. 6. George, V., Varaha, F., Tammisetti, S., Surabhi, V. R., & Shanbhogue, A. K. (2013). Chronic Fibrosing Conditions in Abdominal Imaging 1, 77030. 7. Kipfer, R., Moertel, C., & Dahlin, D. (1974). Mesenteric Lipodystrophy. Annals of Internal Medicine. 582-588. 8. McLaughlin, P. D., Filippone, A., & Maher, M. M. (2013). The “misty mesentery”: mesenteric panniculitis and its mimics. AJR. American Journal of Roentgenology, 200(2), W116–23. 9. Newman, P., Thahal, H., Chaudrey, B. (2014) Mesenteric Panniculitis. BMJ Case Reports. doi:10.1136/bcr-2014-203911 10. Taffel, M. T., Khati, N. J., Hai, N., Yaghmai, V., & Nikolaidis, P. (2014). De-misty-fying the mesentery: an algorithmic approach to neoplastic and non-neoplastic mesenteric abnormalities. Abdominal Imaging, 39(4), 892–907. 11. Corwin, M., Smith, A., Karam, A. & Sheiman, R. (2012). Incidentally detected misty mesentery on CT: Risk of malignancy correlated with mesenteric lymph node size. Journal of Computed Assisted Tomography, 36, 1, 26-29.