Lymphangiomas are uncommon congenital malformations that present mainly in the head, neck, and axillar regions in pediatric patients. Mesenteric cystic lymphangiomas (MCLs), which occasionally present with substantial growth and the invasion of adjacent vital structures, are rarely reported in adults. We report a case of MCL in an adult who was treated with laparoscopic-assisted excision.A 40-year-old Japanese man visited his family physician for prolonged periumbilical pain. Plain computed tomography (CT) showed a low-density mass in his left abdomen, and he was referred to our hospital 2 weeks later. His abdomen was flat and soft, and no mass was felt upon palpation. Routine laboratory data showed no abnormalities in the blood cell counts. The levels of tumor markers, such as carcinoembryonic antigen (CEA), carbohydrate antigen 19-9 (CA19-9), and cancer antigen 125 (CA125), were within normal ranges. Contrast-enhanced CT was performed, and a low-density mass was observed with an irregular outline and poor contrast, as well as involvement of the peripheral mesenteric artery and partial compression of the adjacent jejunum without dilatation of the oral side of the bowel. The patient was diagnosed with lymphatic cysts and observed for 1 month without symptom exacerbation. Follow-up CT showed no increase in the size of the mass but showed apparent invasion of the jejunal wall without bowel obstruction. Magnetic resonance imaging (MRI) showed intermediate intensity on T1-weighted imaging (T1WI) and high intensity on T2-weighted imaging (T2WI). The coronal view on T2WI clearly showed an accumulation of cystic lesions. We performed tumor excision with partial resection of the jejunum in a laparoscopic-assisted manner. Pathological examination showed multicystic lesions with an attenuated endothelial lining, surrounding rich adipose tissue and scattered smooth muscle fibers; the patient was diagnosed with MCL. Immunohistochemical assays supported this diagnosis.This is rare case of MCL presenting in an adult who underwent successful laparoscopic-assisted resection. Mesenteric lymphangioma (ML) should be considered in the differential diagnosis of patients with intraabdominal cysts. Radical excision is optimal, even when the patient is asymptomatic. Laparoscopic-assisted tumor resection is a suitable surgical method for treating MLs located in the peripheral mesentery.
