Intestinal lymphangiectasia is a rare congenital obstructive defect of the lymphatics primarily affecting children and young adults. It is characterized by protein-losing enteropathy, hypoproteinemia, edema, lymphocytopenia, malabsorption, and dilated lacteals. It is part of a generalized disorder of the lymphatic system. Patients also have chylothorax, chyluria, chylous ascites, or asymmetric lymphedema, singly or in combination, depending on the degree of hypoproteinemia (645). Associations of primary intestinal lymphangiectasia are listed in Table 6.55. Hypoplastic visceral lymphatics obstruct lymph flow, causing increased intestinal lymphatic pressure, thereby dilating lymphatic vessels throughout the small bowel and mesentery. Hypoproteinemia and steatorrhea develop secondary to rupture of the dilated lymphatic vessels with discharge of lymph into the bowel lumen. Loss of major plasma protein components leads to hypoproteinemic edema. Serum levels of albumin, immunoglobulins, and other proteins are decreased. Endoscopically, whitish swollen tips of the villi are fairly characteristic.

The intestinal lumen appears dilated and the valves of Kerckring are swollen and broader than normal due to the presence of the dilated lymphatics. The intestines become edematous with a dusky serosa covered by fibrinous exudates. Serosal lymphatics appear as dilated, yellowish nodules measuring <5 mm in diameter. Villi have enlarged bulblike tips imparting a white pebbly papillary appearance to the mucosal surface (Fig. 6.230). The lymphatic channels are dilated and lined by endothelium, contrasting with the changes seen in its mimics (Whipple disease, pneumatosis, and pseudolipomatosis). The reddish brown pigmentation, characteristic of brown bowel syndrome, is often present. Lymphangiectasia is usually a diffuse process, sometimes involving the colon (646). This contrasts with localized lesions such as lymphangiomas or lymphangitic cysts. The diffuse intestinal involvement precludes surgical intervention.