Lymphedema refers to the abnormal accumulation of protein-rich interstitial fluid secondary to lymphatic dysfunction. It may be primary, referring to a developmental abnormality of the lymphatic system, or secondary (acquired). Primary lymphedema is rare in children, with secondary lymphedema being far more common. Primary forms of lymphedema are categorized by age of onset. These include congenital (onset before age 1 year), lymphedema praecox (onset near puberty), and lymphedema tarda (onset after age 30).

Lymphedema praecox is the most common type of primary lymphedema. This condition primarily affects girls, and its onset at puberty or, less commonly, during pregnancy, leads to speculation that estrogen plays a role in its pathogenesis. It usually presents with unilateral involvement of a lower extremity, but involvement can be bilateral; it can also affect upper extremities. Other, more common, secondary causes of lymphedema should be ruled out.  

It is often sporadic, but it is termed Meige disease (type II) if familial. Meige disease is inherited in autosomal-dominant pattern and is associated with lymphedema-distichiasis (double row of eyelashes) syndrome related to a FOXC2 gene mutation. Familial variants may also be associated with yellow nail syndrome (autosomal dominant FOXC2 mutations) or hypotrichosis-lymphedema-telangiectasia syndrome (autosomal dominant or recessive SOX18 mutations).

Lymphedema predisposes patients to infection; thus, cellulitis and other recurrent infections are common. Lymphedema is a chronic ailment that is generally incurable. Treatment is supportive. However, prognosis is favorable with medical management.