Primary lymphoedema is a rare condition caused by inadequate development of the lymphatic system from birth, due to genetic factors. Primary lymphoedema develops as soon as the lymph vessel system can no longer cope with the strain. This usually happens in early life. It is called 'primary' because the impairment is not due to a ‘secondary’ cause like an illness or an injury.
Primary lymphoedema can have different causes:
- Aplasia: Parts of the lymphatic system are missing.
- Hypoplasia: Lymphatic vessels are underdeveloped or present in below-average numbers. This is the most common cause of primary lymphoedema.
- Hyperplasia: Lymphatic vessels are larger than normal and don't work as well as normal-sized vessels.
There are different types of primary lymphoedema and there are many known syndromes that have been linked with it, including Noonan Syndrome, Prader Willi, Yellow Nail Syndrome, and Turner Syndrome.
An example for the congenital onset lymphoedema is Milroy’s disease where the lymphoedema is noticed at birth or shortly afterwards. The late onset primary lymphoedema (e.g. Meige disease) presents at a later stage, with Meige disease usually around puberty.