One function of the lymphatic system is to return excess fluid and protein from interstitial spaces to the blood vascular system. Because lymphatic vessels often lack a basement membrane, they can resorb molecules too large for venous uptake. Mechanisms of clinical edema include increased arteriovenous capillary filtration and reduced interstitial fluid absorption. Causes of increased capillary filtration include increased hydrostatic pressure in capillaries, decreased tissue pressure, and increased membrane permeability. Reduced interstitial fluid resorption can be caused by decreased plasma oncotic pressure, increased oncotic pressure of tissue fluid, and lymphatic obstruction.
The onset of secondary lymphedema is often insidious. However, it may be suddenly provoked by local inflammation from causes such as infection or limb injury. Therefore, patients should be evaluated for evidence of cellulitis. Classically, lymphedema is characterized by nonpitting swelling of an extremity, usually with involvement of the digits. Early stages of lymphedema manifest with pitting edema until fibrosis develops. The distribution of the swelling may be restricted only in the proximal or distal portion of the limb. Lymphedema may also predispose to recurrent skin infections.
Lymphedema can and does occur in the trunk, in addition to the limbs. For example, radiation therapy to the chest wall is associated with the development of edema specifically in the irradiated breast.[6,7]
Patients with lymphedema may report a wide variety of complaints, including heaviness or fullness related to the weight of the limb, a tight sensation of the skin, or decreased flexibility of the affected joint. The texture of the skin may become hyperkeratotic, with verrucous and vesicular skin lesions. With upper-extremity involvement, the patient may have difficulty fitting the affected area into clothing or wearing previously well-fitting rings, watches, or bracelets. Similar difficulties with lower-extremity lymphedema include a sensation of tightness or difficulty wearing shoes, itching of the legs or toes, burning sensation in the legs, or sleep disturbance and loss of hair. Ambulation can be affected because of the increased size and weight of the affected limb. Activities of daily living, hobbies, and the ability to perform previous work tasks may also be affected.
Breast cancer survivors with arm lymphedema have been found to be more disabled, experience a poorer quality of life, and have more psychological distress than do survivors without lymphedema.[8,9] In addition, women reporting swelling have reported significantly lower quality of life with multiple functional assessments.
Lymphedema can occur after any cancer or its treatment that affects lymph node drainage. It has been reported to occur within days and up to 30 years after treatment for breast cancer. Eighty percent of patients experience onset within 3 years of surgery; the remainder develop edema at a rate of 1% per year. Upper-extremity lymphedema most often occurs after breast cancer; lower-extremity lymphedema most often occurs with uterine cancer, prostate cancer, lymphoma, or melanoma. A large population-based study supports the evidence that lower-limb lymphedema is experienced by a significant proportion of women after treatment for gynecological cancer, with the highest prevalence (36%) among vulvar cancer survivors and the lowest prevalence (5%) among ovarian cancer survivors.