By Steve Norton, CDT, CLT-LANA

Lymphedema is characterized by regional immune dysfunction, distorted limb contours, and such skin changes as papillomas, hyperkeratosis, and increased girth. The condition may involve the limbs, face, neck, trunk, and external genitals; its effects may include psychological distress. For optimal patient management, clinicians must understand what causes lymphedema and how it’s diagnosed and treated.
This two-part series provides an over­view of lymphedema. Part 1 covers etiology, pathology, and diagnosis. Part 2, which will appear in the November-
December issue, will focus on treatment.

Causes of lymphedema

Lymphedema occurs when protein-rich fluid accumulates in the interstitium due to impaired lymphatic function. Proteins, other macromolecular wastes, and water constitute lymphatic loads. These wastes rely on specially structured absorptive and transport structures in peripheral regions for their return to central circulation.
When lymph stasis prevails, inflammatory processes and lymphostatic fibrosis trigger tissue-density changes, further entrapping superficial vessels and accelerating mechanical insufficiency. (See Physiologic changes caused by lymphatic disruption by clicking the PDF icon above.)

Classifying lymphedema

Lymphedema can be primary or secondary. Primary lymphedema either is congenital (present at birth) or arises around puberty. In the vast majority of cases, it is associated with structural changes in the lymphatic system and isn’t associated with another disease or condition. Most structural changes (87%) manifest before age 35 and cause hypoplasia of vessels and nodes. Syndromes involving hyperplasia, node fibrosis, or aplasia also may occur, although they’re much less common. Dysplasia (either hypoplasia, hyperplasia, or aplasia) predisposes drainage regions to inadequate lymph collection, resulting in edema and secondary tissue changes, such as chronic inflammation and reactive fibrosis. Genetic variability in lymphatic constitution may explain why seemingly similar patients receiving the same surgical protocol have different lymphedema risks over time.
Secondary lymphedema stems from a significant insult to lymphatic tissues, as from lymphadenectomy, radiation therapy, trauma, infection, or cancer. It commonly results from direct trauma to regional nodes or vessel structures. Slow degradation of lymphatic function also occurs when adjacent tissues (such as superficial and deep veins) become diseased, when cellulitis occurs, or when accumulations
of adipose or radiation fibrosis mechanical-ly disrupt drainage of skin lymphatics.

Lymphedema stages

Lymphedema progresses in stages, which involve secondary connective-tissue disease combined with disturbed fluid update and transport. These conditions cause a universal and classic clinical picture.
•    Stage 0 (latency stage) is marked by reduced transport capacity and functional re­serve. The patient has no visible or palpable edema, but has such subjective complaints as heaviness, tightness, and waterlogged sensations.
•    In Stage 1 edema (reversible lymphedema), edema decreases with elevation. Pitting edema is present, but fibrosis is absent.
•    During Stage 2 (spontaneously irreversible lymphedema), lymphedema doesn’t resolve entirely, although it may fluctuate. Pitting is more pronounced and fibrosis is present.
•    Stage 3 (lymphostatic elephantiasis) is marked by dermal hardening, nonpitting edema, papillomas, hyperkeratosis, and in some cases, extreme girth.

Assessment and diagnosis

Diagnosing lymphedema can be challenging because edema may be associated with other diseases and disorders. For a summary of signs and symptoms, see Clinical findings in lymphedema by clicking the PDF icon above.

Discomfort and skin appearance

Lymphedema rarely causes pain because the skin accommodates gradual, insidious fluid accumulation. However, secondary orthopedic discomfort may result from increased weight of the affected limb due to deconditioning or decreased range of motion.
Because lymphedema usually progresses slowly, gravity and centrifugal forces pull fluids toward distal limb areas, causing an entrenched, stubborn pitting edema. Later, further valvular incompetence contributes to worsening distal edema in the fingers, toes, and dorsal regions of the hand and foot. Prominent lower-extremity structures, such as the malleolus, patella, tibia, anterior tibialis tendon, and Achilles tendon, become progressively less distinct. This creates a columnar limb appearance; the swollen limb has the same girth from distal to proximal aspects, unlike the natural cone shape of a normal limb.
Lymphatic failure doesn’t tax the venous system, so skin color remains normal. Blood supply remains patent, helping to prevent secondary ulcers.

Severity

Lymphedema severity correlates directly with such factors as onset of the condition and extent of cancer therapy, if given (number of nodes resected, number of positive nodes, and use of radiotherapy). Lymphedema may worsen with a greater number of infection episodes, weight gain, injury, diuretics, limb disuse, pneumatic compression therapy (when used for pure lymphedema), and ill-fitting compression garments. The single most important contributor to increasing lymphedema severity is lack of patient education, which can result in improper treatment or none at all.

Opportunistic infections

Lymphedema causes regional immune suppression and leads to an increase in opportunistic infections such as cellulitis. As skin integrity suffers, scaling and dryness allow resident skin pathogens (such as streptococci and staphylococci) to gain access through the defective skin barrier into protein-rich interstitial fluid, creating a medium favorable to bacterial colonization. Lymphocyte migration decreases, and dissected or irradiated nodal sites are slow to detect invaders. Furthermore, stagnant lymph promotes further delays in the immune response. Patients with opportunistic infections may exhibit high fever, local erythema, regional hypersensitivity or acute pain, flulike symptoms, and rapidly advancing “map-like” borders in the skin.

Differential diagnosis

Several methods can aid differential diagnosis.
Clinical findings. Lymphedema can be diagnosed from patient history, physical examination, palpation, and inspection. Trauma to lymph nodes (each of which governs a distinct body region) decreases the transport capacity of lymph formed in that region, in turn causing local swelling (lymphedema). Trauma to the axillary or inguinal lymph nodes, which exist on both the left and right of the body and in both the upper and lower regions, predisposes these quadrants to swelling. Therefore, if lymph nodes on only one side are damaged, lymphedema occurs only on that side of the body. Using the universal characteristics cited above as a guide, while ruling out cancer recurrence, acute deep vein thrombosis, or plasma protein abnormalities, yields sufficient data to form a diagnosis.
Imaging. Lymphography involves sub­cutaneous injection of a lymph vessel–
specific dye (Patent Blue V), followed by X-ray. Although it provides high-resolution images of lymphatic structures, this technique is invasive, painful, damaging to lymphatics, and potentially lethal—and therefore is no longer recommended.
Lymphangioscintigraphy (LAS) uses interdigital subcutaneous injection of protein-labeled radioisotopes, followed by
imaging at specific intervals to gather information about uptake and transport time. Images are hazy and false-negatives are common, so well-trained radiotherapists familiar with lymphology and lymphedema should administer and interpret the test. Also, experts don’t agree on standard criteria for LAS administration, so measures may not be similarly conclusive.
Limb-measuring instruments and methods. Serial measurement of affected limb circumference using a standard garment tape measure is the most widely accessible approach. Intra-rater reliability is comparable to that of currently used tools; however, these methods can’t be used for early detection, for screening, or when various raters are used to assess the same patient. Circumferences are measured at four points and are considered positive if a distance of 2 cm or more separates the involved from uninvolved extremity in comparison. Water displacement techniques for limb-volume calculation, although accurate, are impractical in most clinical settings and rarely used.
Various devices have been used to obtain measurements. For instance, the Perometer® uses optoelectronic volumetry. By scanning the limb with infrared beams circumferentially, the device accurately records girth at 4-mm intervals along the limb length and transmits these measurements to a computer. The Perometer is used mainly in the research setting. Preoperative and postoperative measurements at intervals can detect lymphedema early.
Impedimed XCA® uses bioelectrical
impedance to calculate ratios of intracellular to extracellular fluid. A weak electrical current is passed through affected and unaffected limbs, allowing comparison of results. Impedance is lower in edematous tissue, supporting an accurate diagnosis.

Next step: Treatment

Once a diagnosis is made, the next step is treatment. Part 2 of this series covers lymphedema treatment.

Selected references
Foeldi M. Foeldi’s Textbook of Lymphology: For Physicians and Lymphedema Therapists. 3rd ed. St. Louis, MO: Mosby; 2012.

Kubik S, Manestar M. Anatomy of the lymph capillaries and precollectors of the skin. In: Bollinger A, Partsch H, Wolfe JHN, eds. The Initial Lymphatics. Stuttgart: Thieme-Verlag; 1985:66-74.

Lee B, Andrade M, Bergan J, et al. Diagnosis and treatment of primary lymphedema. Consensus document of the International Union of Phlebology (IUP)—2009. Int Angiol. 2010 Oct;29(5):454-70.

Lerner R. Chronic lymphedema. In: Prasad H, Olsen ER, Sumpio BE, Chang JB, eds. Textbook of Angiology. Springer; 2000.

Mayrovitz HN. Assessing lymphedema by tissue indentation force and local tissue water. Lymphology. 2009 June;42(2):88-98

National Cancer Institute. Lymphedema (PDQ®): Health Professional Version. Updated June 30, 2011. www.cancer.gov/cancertopics/pdq/supportivecare/
lymphedema/healthprofessional. Accessed September 5, 2012.

Northrup KA, Witte MH, Witte CL. Syndromic classification of hereditary lymphedema. Lymphology. 2003 Dec:36(4):162-89.

Olszewski WL. Lymph Stasis: Pathophysiology, Diagnosis and Treatment. CRC Press; 1991.

Pecking AP, Alberini JL, Wartski M, et al. Relationship between lymphoscintigraphy and clinical findings in lower limb lymphedema (LO): toward a comprehensive staging. Lymphology. 2008 Mar;41(1):1-10.

Stanton AW, Northfield JW, Holroyd, B, et al. Validation of an optoelectronic volumeter (Perometer). Lymphology. 1997 June;30(2):77-97

Weissleder H, Schuchhardt C. Lymphedema: Diagnosis and Therapy. 4th ed. Viavital Verlag GmbH; 2007.

Steve Norton is cofounder of Lymphedema & Wound Care Education and executive director of the Norton School of Lymphatic Therapy in Matawan, New Jersey.