Small bowel mesenteric cystic lymphangioma in an adult patient: a rare case report and review of literature.

Introduction and Importance: Mesenteric cystic lymphangiomas are rare intraperitoneal benign tumors of the mesentery. They are thought to arise from lymphatic vessel malformation of unknown etiology during development. They are extremely rare in adults. They occur very rarely in the peritoneum. Preoperative diagnosis is challenging. Radiologic investigations are important, but histopathology is required for definitive diagnosis. Complete surgical excision is the standard treatment. Case Presentation: A 30-year-old male patient presented with mild abdominal pain of 10 years' duration. He appeared chronically unwell. All vital signs were in the normal range. There was a palpable abdominal mass in the right lower quadrant. CT scan suggested mesenteric cystic lymphangioma, which was confirmed by histopathology. Laparotomy with Clinical Discussion: Mesenteric cystic lymphangioma in adults is exceedingly rare and often presents with vague, nonspecific abdominal symptoms, making preoperative diagnosis difficult. Radiologic imaging, particularly CT scan, plays an important role in the diagnosis, but histopathologic examination remains the gold standard. Complete surgical excision with negative margins is the treatment of choice to prevent recurrence and potential complications such as obstruction, perforation, or infection. Conclusion: Mesenteric cystic lymphangioma should be considered in adults presenting with chronic abdominal mass or discomfort. Management options include aspiration and injection of sclerosant agents, radio-frequency ablation, and targeted immune-therapy. However, surgical excision remains the standard curative treatment, preferably via an open approach.