Primary lymphedema is the presence or development of lymphedema without any relation to any underlying medical condition. Primary lymphedema has a quoted incidence of approximately 1-3 births out of every 100,000 births, with a particular female preponderance to male ratio of 3.5:1 worldly. In North America, the incidence of primary lymphedema is approximately 1.15 births out of every 100,000 births.

Primary lymphedema can be classified depending on the age of onset of the patients: at infancy (birth to 1 year), during childhood (1-8 or 9 years), during adolescence (9-21 years), and lastly during adulthood (after 21 years). Mutations in VEGFR3 (Milroy disease), CCBE1 (Hennekam syndrome), SOX18 (hypotrichosis-telangiectasia-lymphedema), and FOXC2 (lymphedema distichiasis) are several eponymous conditions that present at birth and involve the development of lymphedema. Familial lymphedema of the lower extremities that presents itself during adolescence is known as Meige disease. Its underlying genetic abnormality is not known yet, but its familial nature and presentation at adolescence are characteristics of it.

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​Primary lymphedema often occurs at birth and for causes or by mechanisms that are unknown. When primary lymphedema becomes symptomatic in adulthood, these patients often have a long-standing history of lymphedema that is associated with the destruction of lymphatic channels. Adipogenesis or proliferation of adipose tissue coupled with dense fibrosis often results in severe lymphedema of the limb and a more severe presentation. Severe fibrosis occurs with long-standing lymphedema due to the accumulation of protein-rich fluid in the interstitial spaces coupled with inflammation repeated bouts of cellulitis.