Lymphatics in the Alimentary Tract of Children in Health and Disease: Study on Mucosal Biopsies Using the Monoclonal Antibody D2-40

Primary intestinal lymphangiectasia and intestinal lymphatic hypoplasia are 2 causes of protein-losing enteropathy in children and share many common clinical features. For the diagnosis of lymphatic hypoplasia on endoscopic biopsies of the intestine, i.e., based on a negative finding in a small specimen, a very sensitive and specific method for identifying lymphatics is essential. In the present study, lymphatic vessels were labelled using D2-40 immunostaining in mucosal biopsy specimens of the alimentary tract of children in whom no histologic abnormality was noted and of those who had different relatively common pediatric conditions, including inflammatory and neoplastic diseases. Using this method, lymphatic vessels were well visualized even in young infants and not destroyed by diseases. The presence of the muscularis mucosae in specimens was important for adequate assessment. In the duodenum and esophagus, lymphatics were observed in every single section; in the stomach, ileum, and colon, they were less regular and several sections were sometimes required. The extreme sensitivity of this method for demonstrating lymphatic vessels in the duodenum makes it ideal for the histologic diagnosis of intestinal lymphatic hypoplasia. In 4 patients who were considered to have this diagnosis based on clinical features, full-thickness intestinal biopsies and electron microscopy, D2-40 immunostaining confirmed the absence or marked paucity of lymphatics.