Misty Mesentery

The term misty mesentery was coined by Mindelzun et al to "describe the CT appearance of mesenteric fat infiltrated by inflammatory cells, fluid (edema, lymph, and blood), tumor, and fibrosis."

Misty mesentery is seen when the mean density of mesenteric fat increases from <-100 to -40 to -60 HU. The mesenteric vessels may also lose their sharp borders with the surrounding fat. The patient shown here was treated for non-Hodgkin lymphoma. There is a group of mesenteric lymph nodes with increased attenuation in the surrounding fat.

Misty mesentery can be idiopathic or be seen with

• Mesenteric panniculitis
• Edema/lymphedema
• Hemorrhage
• Tumor

At least one group has subdivided misty mesentery into segmental or nonsegmental types. They don't give a definition of nonsegmental misty mesentery, but state that it occurs most commonly in the setting of inflammatory bowel disease or trauma adjacent to the involved bowel.

They define segmental misty mesentery as increased attenuation of the fat around mesenteric vessels with a segmental distribution along the branches of the mesenteric vessels (jejunal, ileal, and ileocolic vessels). Segmental misty mesentery may be seen with mesenteric panniculitis, but not all cases of segmental misty mesentery are necessarily due to mesenteric panniculitis.

References

• Mindelzun et al. The Misty Mesentery on CT: Differential Diagnosis. AJR. 1996;167 (1): 61.
• Seo BK, Ha HK, Kim AY, Kim TK, Kim MJ, Byun JH, Kim PN, Lee MG, Yang SK, Yu ES, Kim JH. Segmental misty mesentery: analysis of CT features and primary causes. Radiology. 2003 Jan;226(1):86-94.