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The two major types of lymphedema include:

• Primary lymphedema
• Secondary lymphedema

Primary Lymphedema

Primary lymphedema is a rare congenital or inherited condition in which the lymph nodes or lymphatic vessels are either absent or abnormal. The vessels may be characterized by:

• Hypoplasia - the lymph collector vessels are so small that they are ineffective
• Hyperplasia - the lymph vessels are too large and are ineffective
• Aplasia - absence of lymph vessels that lead to the lymph nodes

Primary lymphedema is usually apparent at birth or within the first two years of life and has been linked to several genetic chromosomal abnormalities. Swelling usually affects one lower leg however, edema may also be present in multiple limbs, the genitalia, and face.

There are three types of primary lymphedema:

• Congenital lymphedema - This form accounts for up to 25% of cases of primary lymphedema. It affects females twice as often as males and is three times more likely to affect the legs than the arms. Most cases are bilateral (either both arms or both legs) and, while rare, it can also effect the face and genitalia.

• Lymphedema praecox - This is the most common form of primary lymphedema and accounts for approximately 90% of all cases. It affects women more than men by a ratio of about 10 to 1 and usually emerges during puberty. Most cases are unilateral and are limited to the foot or calf.

• Lymphedema tarda also known as Meige Disease - this form of lymphedema becomes apparent only after the age of 35 and accounts for less than 10% of cases of primary lymphedema. Typically, patients have an overabundance of vessels which are very tortuous with many oddly shaped bends and turns. Valves are often absent or malfunctioning.

Secondary Lymphedema

Secondary lymphedema (called 'lymphedema' in the remainder of the Guidebook) is lymphedema caused by a blockage or interruption of the lymphatic system usually involving the lymph nodes in the groin or armpit area. There is usually an identifiable cause for the inadequate functioning of the lymphatic system such as cancer surgery or radiotherapy. Other causes include:

• Vein stripping (a procedure to remove varicose veins)
• Peripheral vascular surgery
• Burns
• Insect bites
• Infection
• Inflammation
• Trauma

Secondary lymphedema of the arm is most likely to occur following radiotherapy for breast cancer or axillary lymph node dissection (ALND), a procedure used to determine the extent of spread of breast cancer which involves removal of several lymph nodes in the armpit area. This is the most common cause of secondary lymphedema in the US. Lower limb lymphedema follows in up to 47% of patients who have undergone pelvic or genital cancer surgery especially if a procedure involving inguinal or pelvic lymph node dissection or irradiation is performed.

Secondary lymphedema can be further subdivided into acute and chronic subtypes.

Acute Lymphedema

According the National Cancer Institute, there are 4 types of acute lymphedema:

• The first type of acute lymphedema occurs within a few days following the surgical removal of lymph nodes and is typically mild and temporary. This lymphedema usually resolves within a week or two if the limb is elevated and the muscles of the limb are periodically contracted.