PRIMARY AND SECONDARY LYMPHEDEMA
There are two types of lymphedema - primary and secondary. Both types relate to lymph vessels or lymph nodes that are missing, damaged, removed or otherwise impaired. Additionally, lymphedema can be classified as benign or malignant.
Primary lymphedema is due to a developmental defect (malformation, dysplasia) of the lymph vessels and/or lymph nodes. Primary lymphedema can be either congenital or hereditary.
Primary lymphedema can present as a variety of congential abnormalities:
- Aplasia: Lymph collectors, capillaries or lymph nodes are inherently missing.
- Hypoplasia: The diameter of the lymph collectors is reduced and/or the number of collectors is below normal level.
- Hyperplasia: The diameter of the initial lymphatics and/or lymph collectors is larger than normal.
Primary lymphedema is also classified according to age of onset:
- Hereditary Lymphedema (Noone-Milroy Syndrome) - Onset at birth.
- Hereditary Lymphedema II (Lymphedema Praecox Meige) - Onset age 10-35
- Hereditary Lymphedema III (Lymphedema Tarda) - Onset age 35+
Caused by an insult to the lymphatic system and can appear at any age. Causes may include:
- Surgery/radiation for cancer: Lymph node dissection that is often associated with cancer therapy can disrupt lymph flow.
- Radiation for cancer: Radiation can cause tissue fibrosis which can impair lymph flow.
- Cancer. Malignant tumors can grow and compress lymph vessels and decrease flow. Also, cancer cells can penetrate lymph vessels and proliferate and block flow.
- Trauma: Crushing injuries, burns, and other traumas to the body can affect the lymphatic vessels inhibiting flow.
- Iatrogenic: Due to major surgical, minor surgical (ex pacemaker placement can be a rare cause) or even interventional procedures (cardiac catherization can be a rare cause of lymphedema) even in the absence of any other complication related to the procedure.
- Infection: Chronic or recurrent bouts of acute lymphangitis can cause damage to the lymphatic vessels.
- Chronic Venous insufficiency: The constant increased strain placed on the lymphatic system from increased filtration from CVI can cause lymphatic insufficiency. This is referred to as Phlebolymphedema. Patients with CVI and phlebolymphedema often have underlying contributing factors: heart failure, renal failure, untreated sleep apnea, pulmonary hypertension, severe obesity, paresis / paralysis and limb dependency, as well as certain medications.
- Obesity: The increased lymphatic load associated with obesity, often in conjunction with increased pressure on lymph nodes, can impair lymphatic flow.
- Filariasis: A parasitic disease caused by microscopic worms that are transmitted when an infected mosquito bites a person. The adult worms live in the lymphatic system and lead to impairment.