E3333. Unusual Mesenteric Masses and Masslike Processes
  1. Seng Thipphavong; Princess Margaret Cancer Centre
The mesentery is a large organ which can harbor many pathologies. Mesenteric pathologies can range from benign processes such as mesenteric panniculitis to malignancies like sarcomas. The ability to confidently differentiate a benign process requiring no biopsy from an aggressive mass is crucial in directing patient care. Many infectious or benign processes have typical imaging appearances and can be easily diagnosed. However, there are several primary benign mesenteric neoplasms which can be confused for malignancies. The purpose of this exhibit is to review a wide variety of mesenteric processes with a focus on unusual or infrequently encountered processes and masses.

Educational Goals / Teaching Points
Unusual benign masslike mesenteric processes include amyloidosis and mesenteric sclerosis. Infrequently encountered primary benign mesenteric masses include fibromatosis, lipoma, and nerve sheath tumors. Primary sarcomas that can arise from the mesenteric include liposarcoma and leiomyosarcoma.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Showcase of not-frequently-encountered pathologies involving the mesentery: a. Unusual appearance of infection and benign masslike processes (tuberculosis, amyloidosis, mesenteric sclerosis, CSF pseudocyst, large aneurysm); unusual primary benign mesenteric neoplasms (lymphangioma, fibromatosis, lipoma, Castleman's disease, schwannoma); and large primary and secondary malignant masses (gastrointestinal stromal tumor, leiomyosarcoma, liposarcoma [well-differentiated and dedifferentiated]). Take home points for diagnosis.

A wide spectrum of pathologies can occur in the mesentery, ranging from nonneoplastic processes to malignant masses. There are several benign mesenteric processes with typical imaging appearances that do not require a tissue sample for diagnosis such as lymphangiomas or pseudocysts. However, atypical appearances of benign processes can occur, and radiologists should be aware to avoid unnecessary biopsies. Conversely, soft tissue masses in the mesentery such as schwannoma, fibromatosis, GIST, leiomyosarcoma, and liposarcoma often require a biopsy for definitive diagnosis.