Incidentally detected misty mesentery on CT: risk of malignancy correlates with mesenteric lymph node size.

OBJECTIVE: To determine the natural history of incidentally detected misty mesentery on computed tomography (CT) and to correlate the risk of malignancy with size of mesenteric lymph nodes.

METHODS: A retrospective review of all CT abdomen/pelvic examinations from January 1, 2004 through December 31, 2008 identified cases of misty mesentery. The largest mesenteric lymph node was measured, and additional areas of lymphadenopathy were identified. Follow-up was obtained by reviewing all subsequent CT examinations, clinical notes, and pathologic specimens. Patients were excluded if they had a known malignancy at the time of initial CT, CT or clinical history revealing a cause for the misty mesentery, or CT follow-up of less than 2 years.

RESULTS: Thirty-seven patients with misty mesentery were included. The mean time from the original CT to the latest follow-up was 3.8 years. The largest lymph node measured less than 10 mm in 30 (81%) of 37 patients. All 30 patients demonstrated stable lymph node size, had no other regions with lymphadenopathy, and none developed malignancy. The largest lymph node was 10 mm or greater in 7 (19%) of 31 patients. Three of these patients developed non-Hodgkin lymphoma, 2 of which had other areas of lymphadenopathy. No cases of nonlymphomatous malignancy were identified.

CONCLUSIONS: The development of malignancy in patients with incidentally detected misty mesentery correlates with mesenteric lymph node size. Patients with misty mesentery and largest mesenteric lymph node less than 10 mm without additional areas of lymphadenopathy demonstrate a benign course, and no further follow-up may be necessary.