Abnormalities of Lymphatic Vessels

Chapter 483 Abnormalities of Lymphatic Vessels

Abnormalities of the lymph vessels may be congenital or acquired. Signs and symptoms result from increased lymphatic tissue mass or from leakage of lymph. Lymphangiectasia is dilation of the lymphatics. Pulmonary lymphangiectasia causes respiratory distress (Chapter 387.6). Involvement of the intestinal lymphatics causes hypoproteinemia and lymphocytopenia secondary to loss of lymph into the intestines (Chapter 330). Therapy includes minimizing the hydrostatic pressure in the lymphatic system, leading to decreased protein loss. Reducing dietary intake of long chain fatty acids and substituting medium chain triglycerides via formula accomplishes this goal. Lymphangioma is a congenital lymphatic malformation, usually detected by the age of 2 yr. Lymphangioma circumscriptum is defined as the presence of many small, superficial lymphangiomas. Deeper lymphangiomas are classified as either cavernous lymphangiomas or cystic hygromas. Lymphangiomatosis is the presence of multiple or disseminated malformations. Some of these lesions also have a hemangiomatous component (Chapter 499). Emergent surgical treatment is infrequently necessary due to mass effects. Most lesions may be observed for 18-24 mo to assess for involution. Surgery is effective for superficial lesions, but is complicated by a high incidence of recurrence when used for deeper lesions. Intralesional sclerosing with a streptococcal derivative called OK-432 has been used successfully in selected patients. Other sclerotherapy agents include pure ethanol and bleomycin. Macrocystic lesions appear to respond better than microcystic lymphangiomas to sclerotherapy. Radiofrequency ablation has been used for lymphatic lesions of the tongue. Lymphatic dysplasia may cause multisystem problems, including lymphedema, chylous ascites, chylothorax, and lymphangiomas of the bone, lung, or other sites.

Lymphedema is localized swelling due to impaired lymphatic flow and can be congenital or acquired. Congenital lymphedema may be found in Turner syndrome, Noonan syndrome, and the autosomal dominantly inherited Milroy disease, among other chromosomal abnormalities. Several families with Milroy disease have mutations in the vascular endothelial growth factor receptor-3 gene (VEGFR-3). Autosomal recessive and X-linked inheritance has also been reported. Lymphedema praecox (Meige disease) causes progressive lower extremity edema, usually in females during the peripubertal period or during pregnancy. Hypotrichosis-lymphedema-telangiectasia syndrome has dominant and recessive inheritance patterns and has been linked to mutations in SOX18. Podoplanin/T1α mutations may also lead to congenital lymphedema. Lymphedema has also been found in association with intestinal lymphangiectasia, cerebrovascular malformation, ptosis, yellow dystrophic nails, distichiasis, and cholestasis. Mutations in FOXC2 are associated with lymphedema-distichiasis syndrome, which has a pubertal onset of lymphedema. Acquired obstruction of the lymphatics can result from tumor, postirradiation fibrosis, and postinflammatory scarring. Filariasis is an important cause of lymphedema in Africa, Asia, and Latin America; of the estimated 120 million infected persons, approximately 40 million (primarily older adolescents and adults) are believed to have lymphedema or hydrocele. Injury to the major lymphatic vessels can cause collection of lymph fluid in the abdomen (chylous ascites) or chest (chylothorax). Untreated lymphedema can be disabling and is associated with immune dysfunction, inflammation, fibrosis, and adipose tissue overgrowth. Current treatment modalities attempt to reduce localized swelling through massage, exercise, and compression. No drugs have been proven efficacious, and diuretic use should be avoided. The recently discovered gene mutations provide potential targets for gene therapy. Use of growth factors to stimulate lymphangiogenesis may also be on the horizon.

Lymphangitis is an inflammation of the lymphatics that drain an area of infection. Tender, erythematous streaks extend proximally from the infected area. Regional nodes may also be tender. Group A streptococci and Staphylococcus aureus are the most frequent pathogens, and therapy should include antibiotics that treat these organisms.

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