Mesenteric fat has a same density as the fat in the subcutaneous tissue {- 100 to -160 HU}. Infiltration of the increases the density to {- 40 to -60 HU } with loss of the sharp interface with the vascular structures – a hazy appearance that is often referred to as a “Misty Mesentery”

The mesentery is a double fold of the peritoneum. True mesenteries {the small bowel, the transverse mesocolon and the sigmoid} all connect to the posterior peritoneal wall. Some mesenteries do not connect to the posterior peritoneal wall-- The greater omentum: connects the stomach to the colon The lesser omentum: connects the stomach to the liver The mesoappendix: connects the appendix to the ileum Thesmall bowel mesenteryis a broad fan-shaped fold ofperitoneumconnecting the loops ofjejunumandileumto the posterior abdominal wall Its connection with the posterior abdominal wall,...

It can occur due to infiltration of the mesenteric fat with inflammatory cells, fluid (oedema, lymph, blood), malignant cells and fibrosis In the normal mesentery, the blood vessels are clearly visualised due to low attenuation of the mesenteric fat In case of misty mesentery, the vessels lose their sharp interfaces and may be partially / completely effaced; Typical features include a left-sided distribution, a ‘fat halo’ sign, nodules and a pseudotumorous hyperdense stripe. Mildly enlarged lymph nodes are seen, calcification may rarely be seen. It...

The appearance of Misty Mesentery could be an incidental finding on CT, however an underlying cause should always be excluded. The prevalence of mesenteric panniculitis on CT scans is around 0.6%.Typical features include a left-sided distribution, a ‘fat halo’ sign, nodules and a pseudotumorous hyperattenuation stripe{ pseudocapsule}

T Simelane, Consultant Radiologist H Khosa Consultant Radiologist Midland Regional Hospital, Portlaoise, Ireland N Ramesh Consultant Radiologist Midland Regional Hospital, Portlaoise, Ireland

1. The misty mesentery: mesenteric panniculitis and it mimics P McLaughlin, A Filippone, M Maher, AJR, Feb 2013, Vol 200, No. 2 , W116-W123 2. Misty mesentery: pictorial review of multidetector row CT findings. A Filippone, A Cianci, ML Storto, Radiol Med 2011, 116.351-365 3. Incidentally detected misty mesentery on CT: Risk of malignancy correlates with mesenteric lymph node sizeMT Corwin, AJ Smith. RG Sheirman, J Comp Assist Tomogr, 2012, Jan-Feb: 36 {1}:26-9: doi: 10.1097/RCT.0b013e3182436c4d 4. CT findings in mesenteric panniculitis : Case 8685 Eurorad:...