Abstract
INTRODUCTION: Giant retroperitoneal mesenteric cysts are extremely rare and can present with nonspecific symptoms. Their origin remains unclear, and complete surgical excision is the definitive treatment. CASE PRESENTATION: We describe a young girl with progressive abdominal distension. Imaging showed a large intra-abdominal cyst of uncertain origin. Surgical exploration revealed a retroperitoneal mesenteric cyst, which was completely excised. CLINICAL DISCUSSION: Although rare, these cysts should be included in the differential diagnosis of abdominal masses, especially in atypical presentations. Accurate diagnosis often requires surgical intervention, which allows for histopathological evaluation and exclusion of malignancy. CONCLUSION: Surgical excision serves both diagnostic and therapeutic purposes. While outcomes are generally favorable, the underlying mechanisms of these lesions remain unclear, highlighting the need for further research.