Giant Mesenteric Lymphangioma in a Young Adult: A Rare Clinical Entity.

Cystic lymphangioma is a rare benign tumor of lymphatic origin, characterized by slow growth and variable clinical presentation. The presence of a peritoneal diverticulum is exceedingly rare in adults and often poses a diagnostic challenge owing to nonspecific symptoms and imaging findings. A 22-year-old previously healthy male presented with abdominal fullness and flatulence without other relevant symptoms. On physical examination, a firm, palpable abdominal mass was identified. Laboratory tests revealed mild elevations in alanine aminotransferase and alkaline phosphatase levels. Abdominal computed tomography (CT) revealed a cystic lesion in the epigastric and right hypochondriac regions adjacent to the liver, pancreas, and stomach. Magnetic resonance imaging (MRI) revealed a cystic mass suggestive of lymphangioma, measuring 21 cm × 20 cm × 16 cm. The patient underwent open retroperitoneal lymphadenectomy with complete excision of the lesion and additional foci located above the superior mesenteric vein. Histopathological examination confirmed the diagnosis of mesenteric cystic lymphangioma. Mesenteric lymphangiomas are rare in adults and present with vague, nonspecific abdominal symptoms. Imaging studies play an essential role in diagnosis, although definitive confirmation requires histopathological evaluation of the tissue. Complete surgical resection remains the treatment of choice and is critical for preventing recurrence and potential complications, such as infection, rupture, or intestinal obstruction. Given the rarity and diagnostic challenges of mesenteric cystic lymphangioma in adults, clinicians should maintain a high index of suspicion when evaluating abdominal cystic lesions in adults. Early surgical intervention is fundamental for achieving optimal outcomes and preventing future complications.