Malignant transformation of benign mesenteric cyst.

We describe the clinical and pathological features of a case of mesenteric cyst which was incompletely excised, recurred over several years, and eventually underwent malignant transformation. A review of the literature shows how mesenteric cysts are still poorly understood clinical entities, often difficult to classify even after histopathological evaluation. This is the first reported case of transformation of a benign mesenteric cyst into adenocarcinoma. Complete excision of all mesenteric cysts should be carried out, to prevent recurrence and possible malignant transformation.