Misty mesentery sign | Radiology Signs

Answer:

The misty mesentery sign reflects a pathological increase in mesenteric fat attenuation on CT imaging caused by fluid infiltration (edema), hemorrhage, inflammation, neoplastic cells, or fibrosis within the mesentery. It is a nonspecific radiological finding associated with various underlying pathologies:

• Mesenteric panniculitis (chronic inflammatory and fibrotic disorder of the mesenteric fat)
• Infections (e.g., tuberculosis)
• Neoplasms (e.g., lymphoma)
• Trauma
• Vascular disorders
• Systemic diseases (e.g., cirrhosis, hypoalbuminemia)

Why is it called so?

The term “misty” describes the hazy or foggy appearance of the mesenteric fat on CT scans, which normally shows low attenuation due to its fatty content. Pathologic processes increase fat density, producing a “mist-like” appearance on the mesenteric CT images.

Pathophysiology

The sign develops when abnormal accumulation of fluid, cellular infiltrates (inflammatory or neoplastic cells), hemorrhage, or fibrotic tissue replaces or infiltrates the normal low-attenuation mesenteric fat. This raises attenuation values from typically less than -100 Hounsfield units (HU) to higher levels, creating a muddled, hazy appearance. Additional findings such as adjacent lymphadenopathy and soft-tissue strands often accompany this feature depending on the underlying condition.

Alternative names: None

Other associated named signs:

• Fat halo sign – a spared fat halo around mesenteric vessels seen in mesenteric panniculitis
• Tumoral pseudocapsule sign – a peripheral curvilinear soft-tissue band occasionally seen in mesenteric panniculitis

Detailed article: http://radiogyan.com/cases/misty-mesentery-sclerosing-mesenteritis/