The lymphatic vasculature is an integral component of the circulatory and immune systems.1 It is composed of a network of vessels that interconnect the body's interstitial spaces with the lymphoid organs (lymph nodes, spleen, thymus, and so on) and the systemic circulation. The lymphatic system is essential in maintaining the fluid homeostasis and optimal functioning of the immune system. Unlike the circulation of blood in the vascular system, lymphatic flow occurs through a low-pressure system. The interstitial fluid enters the distal lymphatics which coalesce into conduits of increasing caliber, ultimately draining lymph into the systemic circulation through the thoracic duct.
Lymphatics are found throughout the body, with the exception of the central nervous system, where the cerebrospinal fluid fulfills the role of the lymph. Lymphatic vasculature and lymphoid tissues are prevalent in organs that come in direct contact with the external environment, such as the skin, gastrointestinal (GI) tract, and lungs. This is reflective of the protective role of the lymphatics against infections. In the extremities, the lymphatic system consists of a superficial system that collects lymph from the skin and subcutaneous tissues and a deeper system that drains subfascial structures such as muscle, bone, and deep vasculature. The superficial and deep systems of the upper and lower extremities merge in the axillae and pelvis respectively. The two drainage systems function in an interdependent fashion such that the deep lymphatic system participates in lymph transport from the skin during superficial lymphatic obstruction. The superficial and deep systems drain at markedly different rates. In the normal leg, subfascial transport (the deep system) is slower than the superficial system and transports less lymph.
A wide spectrum of disease states result in an impaired ability of the lymphatic system to collect and transport lymph. Lymphedema is a condition associated with nonpitting swelling or edema usually associated with an extremity caused by an abnormality of the lymphatic system and is often difficult to treat. It is a chronic debilitating disease that is frequently misdiagnosed, treated too late, or not treated at all. It results from impaired lymphatic transport caused by injury to the lymphatics, infection, or a congenital abnormality (hypoplasia or aplasia). Common etiologies include sequelae of breast and pelvic cancer therapy, recurrent infections, injuries, and vascular surgery. Approximately 10 million people have lymphedema secondary to breast and pelvic cancer therapy, recurrent infections, injuries, or vascular surgery. Worldwide, about 90 million people have lymphedema, primarily because of parasitic infection; the most common cause is filariasis caused by Wuchereria bancrofti infection.2
The diagnosis of lymphedema relies heavily on the physical examination. Characteristic clinical findings include edema, peau d'orange, cutaneous fibrosis, and a positive Stemmer sign (inability of the examiner to tent the skin at the base of the digits in the involved extremity). If the diagnosis remains in question, the presence of lymphatic vascular insuffiency ...