• Lymphedema is a chronic progressive swelling in subcutaneous tissues, typically in an extremity or the genitals, due to protein-rich accumulation of interstitial fluid from disruption of the lymphatic system. It can be of primary or secondary origin.
  • Primary lymphedema has three forms, all of which stem from a developmental abnormality of lymphatic flow. Not all primary lymphedemas are clinically evident at birth.
    • Congenital lymphedema, due to anomalous development of lymph system
      • Present at birth
      • Lower to upper extremity ratio: 3:1
      • 2/3 of cases are bilateral.
      • May improve with age
    • Lymphedema praecox (65–80% of primary lymphedema)
      • Usually becomes evident at puberty but may appear between infancy and age 35 years
      • 70% unilateral lower extremity (L > R)
    • Lymphedema tarda: presents at age 35 years or older
  • Secondary lymphedema is from an acquired abnormality of lymphatic flow, an injury to the lymphatic system.
    • Common causes in children include the following:
      • Postsurgical obstruction
      • Burns
      • Insect bites
      • Infection
      • Scar tissue from radiation
      • Neoplasm
      • Trauma
  • Classification: There are several systems for grading the severity of lymphedema.
    • The International Society of Lymphology (ISL) describes lymphedema using skin consistency and outcome.
      • Stage 0: dormant condition where a patient might describe their extremity as heavy
      • Stage I (mild): soft tissue that may pit, no dermal fibrosis; improves with elevation of extremity
      • Stage II (moderate): evolving dermal fibrosis that does not pit; no improvement with limb elevation
      • Stage III (severe): Tissue is swollen and thick; there may be peeling, discoloration, or trophic changes.
    • The American Physical Therapy Association (APTA) describes lymphedema by measurement between the affected and unaffected extremity.
      • Mild: girth difference <3 cm
      • Moderate: girth difference of 3 to 5 cm
      • Severe: girth difference of >5 cm


  • Most lymphedemas in childhood are primary (or idiopathic) lymphedema (96%).
  • Congenital lymphedema comprises 10–25% of primary lymphedema cases; lymphedema praecox, 65–80%; and lymphedema tarda, 10%.
  • Affected males—most likely congenital and bilateral; affected females—most likely unilateral lymphedema praecox
  • Secondary lymphedema is more common in adults and rare in children. In the United States, it is commonly from breast cancer; worldwide, due to filariasis
  • Affects 1.15 of 100,000 in children <20 years

Risk Factors


  • Milroy disease
    • Also known as hereditary lymphedema type IA
    • A rare, autosomal dominant condition that affects lymphatic function
    • Associated with mutations in the FLT4 gene that encodes vascular endothelial growth factor receptor 3
  • Meige disease
    • Hereditary lymphedema type II—familial lymphedema praecox
  • Fabry disease
    • A serious, X-linked inborn error of glycosphingolipid catabolism associated with progressive renal failure, cardiovascular disease, neuropathy, and angiokeratosis
  • Lymphedema-distichiasis
    • An autosomal dominant condition that presents with lymphedema and double rows of eyelashes
    • The condition is associated with mutations in the FOXC2 gene.
  • Other genetic conditions prone to lymphedema: Down, Turner, Noonan, yellow nail, Klippel-Trenaunay-Weber, and pes cavus


  • Abnormal accumulation of interstitial fluid due to the lymphatic load overwhelming the transport capacity of lymph vessels
  • Lymph flow occurs under a low pressure system; unlike generalized edema, capillary filtration remains normal in patients with lymphedema.
  • Initially, edema is pitting, whereas chronic edema is generally nonpitting as a result of fibrosis.

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