Mesentery represents double layer of peritoneum that encloses an organ and connects it to the posterior abdominal wall.
The fundamental histological elements of the mesentery are the surface mesothelium and the core made of adipocyte containing loose connective tissue which provides a lattice to lymph nodes,
blood vessels and nerves passing to and from viscera.
(1)
Traditionally,
mesentery was thought to consist of three parts: small bowel mesentery,
transverse and sigmoid mesocolon.
However,
novel findings imply that the mesentery distal to the duodenojejunal flexure is a contiguous structure which commences at the root of superior mesenteric artery and fans out to rectum containing also left and right mesocolon - which are flattened against the posterior abdominal wall.
It represents unique,
uninterrupted suspensory system of the bowel who’s role in mediation of local and systemic responses (such as production of C- reactive protein),
maintaining homeostasis and providing pathways for a disease spread from the bowel,
is yet to be determined.(1)
The term “misty mesentery” coined by Mindelzun et al.
in AJR 1996 (2) denotes a CT appearance of increased attenuation of the mesentery with fat stranding and induration due to infiltration of the mesenteric fat by
1. inflammatory cells,
2. fluid (edema,
lymph,
and blood),
3. tumor,
4. fibrosis
“Misty mesentery” is an unspecific sign and both primary diseases of the mesentery as well as the diseases which originate the surrounding organs may cause such an appearance on CT.
In patients suffering from acute abdominal disease,
“misty mesentery” may be considered a feature of the underlying disease.
On the other hand,
it often represents an incidental finding on CT examination performed for other reason and that is when knowledge of certain characteristic CT signs may together with clinical picture,
laboratory results and findings on the surrounding organs suggest the right diagnosis or at least narrow its differential.
(3)
Common causes of “misty mesentery” include: Acute pancreatitis,
portal hypertension,
heart or renal failure,
peritonitis,
lymphoma,
sclerosing mesenteritis,
diverticulitis,
Chron’s disease,
ischemic enteritis,
postsurgical mesenteric infiltration,
carcinoid tumor.
Less common causes are: mesenteric trauma,
vasculitis,
radiation enteritis,
peritoneal metastases,
portal or SMV thrombosis,
mesothelioma,
lymphangiectasia intestinal,
coagulopathic hemorrhage,
leukemic infiltration of peritoneum (4)