Sumo, a 1-year-and-2-month-old Syrian hamster, presented for a routine health check. Physical examination showed a bright, alert hamster with normal hydration and body condition. Abdominal ultrasonography revealed a well-defined capsule with hyperechoic round echoes and anechoic effusion along the small intestinal vessel, measuring 1.22 × 0.55 cm (sagittal) and 0.87 × 0.60 cm (transverse). CT imaging confirmed a round, soft tissue density near the cranial mesenteric vessel. Initial treatment with metronidazole (3.5 mg) and meloxicam (0.08 mg) for one week did not resolve the condition. Following the owner's approval, the hamster underwent surgical excision of the abnormal structure. The capsule ruptured during dissection, necessitating abdominal lavage and closure using a simple interrupted appositional suture pattern. The hamster recovered well, and the surgical site healed without complications. Histopathology revealed moderate reactive hyperplasia of the lymph node and severe necrotic tissue lymphedema. Bacterial culture and sensitivity testing showed no bacterial growth. Lymphedema, caused by dysfunction of the lymphatic circulatory system, is rare in veterinary medicine and is usually associated with lymph nodes of extremities. To the authors' knowledge, this is the first documented case of mesenteric lymphedema in a Syrian hamster.