AbstractMesenteric masses are infrequent lesions ranging from benign cysts to aggressive malignancies and often present a diagnostic and therapeutic challenge. The mesentery is a frequent recipient of metastases from the gastrointestinal tract, pancreas, and biliary cancers. Primary mesenteric tumors are relatively rare, mostly mesenchymal in origin and benign in nature. Examples include gastrointestinal stromal tumors and smooth muscle tumors. We describe a 50-year-old woman, who presented with a lump in the left hypochondrium along with altered bowel habits of 2 years’ duration. Imaging revealed a cystic lesion, raising the differentials of a benign lesion. Exploratory laparotomy revealed a large cystic mass in the mesentery closely abutting the jejunal loops. This was followed by mass resection along with a segment of the jejunum. Histopathological examination revealed features of a leiomyosarcoma. Postoperatively, the patient developed a colocutaneous fistula, which was re-excised. At 6 months’ follow-up, the patient is doing well. Our case demonstrates the diagnostic challenge posed by the atypical clinical and imaging features of this tumor at an unusual site.