Primary malignant fibrous histiocytoma of the mesocolon transversum.

Primary malignant fibrous histiocytoma (MFH) is a rare and biologically aggressive tumor. Differential diagnosis must include cystic neoplasms of the pancreas (mucinous and serous cystoadenoma or cystocarcinoma), cystic lymphangioma or mesothelioma and retroperitoneal haematoma. Making the right diagnosis preoperatively may be often difficult, but MFH may be suspected when a huge retroperitoneal mass is found at imaging in elderly patients. We report a case of a primary abdominal MFH originating from the mesocolon transversum.