Primary lymphedema is a rare inherited or congenital condition in which the lymph nodes or lymph vessels are either absent or abnormal. The vessels may be characterized by hypoplasia (lymphatic vessels are so small that they are ineffective), hyperplasia (lymphatic vessels are so large that they are ineffective), or aplasia (absence of lymphatic vessels leading to the lymph nodes). Primary lymphedema is usually apparent from birth or within the first two years of life and has been linked to many genetic chromosomal abnormalities. Edema usually affects the lower extremities, but may be evident on all limbs, genitals, and face. There are three types of primary lymphedema:
Α) Congenital Lymphedema : This form corresponds to 25% of cases of primary lymphedema. It affects women twice as often as men and is three times more likely to affect the lower extremities than the upper extremities. Most cases involve both extremities (either upper or lower extremities) and although it is rare, it can also affect the face and genitals.
Β) Lymphedema Praecox:This is the most common form of primary lymphedema and accounts for 90% of cases. It affects women more often than men by a ratio of 10 to 1 and usually becomes apparent during adolescence. Most cases involve only one limb and are limited to the foot and shin .
Γ) Delayed Lymphedema (Tarda):This type of lymphedema becomes apparent only after the age of 35 and corresponds to less than 10% of cases primary lymphedema. Typically patients have an excessive number of vessels that are very tortuous with many of them being oddly shaped. .