A 55-year-old female presenting with non-specific central abdominal pain and vomiting was referred for MDCT of the abdomen (Image 1 axial CT).
KeywordsHeart Failure Adipose Tissue Hounsfield Unit Rectal Bleeding Abdominal Mass
Describe the appearance of the mesenteric fat.
What diagnoses should be considered?
The central mesenteric fat, around the mesenteric vessels (long arrow Image 2), is hyper-attenuating and has a subtle pseudo-capsule (short arrows Image 2).
Sclerosing mesenteritis (SM), but there is a wide differential (see text below).
‘Misty mesentery’ is the term used to describe hyper-attenuating mesenteric fat seen on CT and raises the possibility of ‘sclerosing mesenteritis’ (SM). SM is a non-specific, benign inflammatory process affecting the adipose tissue of the mesentery of unknown cause. It is known by many other names including mesenteric panniculitis, Weber-Christian disease, to name but two.
The clinical features are non-specific and can include abdominal pain, vomiting, weight loss and rectal bleeding. An abdominal mass can be palpitated in 50% of patients. SM generally has a self-limiting course.
CT demonstrates the fat in the affected area to have attenuation values of between –40 and –60 Hounsfield units (as opposed to –100 to –160 normally). The mesenteric vessels are encased but not displaced; there are soft tissues nodules (usually less than 5 mm) in 80% and a thin (less than 3 mm) pseudo-capsule in 50%.
‘Misty mesentery’ can occur in many other conditions including malignancy (such as NHL (arrows Image 3), carcinoid and desmoids), inflammation such as pancreatitis and mesenteric oedema from any cause, i.e. cirrhosis, heart failure.
Because of this differential diagnosis biopsy is sometimes performed unless the CT features are typical of SM – see above.
Misty mesentry is hyper-attenuating fat seen on CT.
There are several causes ranging from self-limiting SM to NHL.