A histopathological diagnosis of mesenteric cystic lymphangioma, clinically misdiagnosed as simple mesenteric cyst - case report.

Abdominal cystic lymphangiomas are relatively rare congenital malformations, predominantly found in the pediatric age group. They are usually found in the head and neck of affected children. Lymphangioma of the small-bowel mesentery is rare, having been reported for less than 1% of all lymphangiomas. The gross and histopathological findings may resemble benign multicystic mesothelioma and lymphangiomyoma. The immunohistochemical study for factor VIII-related antigen, D2-40, calretinin and human melanoma black-45 (HMB-45) is essential for diagnosis. Factor VIII-related antigen and D2-40 are positive in lymphangioma but negative in benign multicystic mesothelioma. HMB-45 shows positivity in the smooth-muscle cells around the lymphatic spaces of the lymphangiomyoma. This report describes a case of a large mesenteric lymphatic cyst identified in the neonatal period. Early diagnosis was possible due to the prenatal imagistic methods. Fetal ultrasound identified in the 17th week of gestational life an abdominal tumor that increased with fetal growth. The anatomopathological differential diagnosis and modalities of treatment are also discussed.