4. Lymphatic Obstruction
The lymphatic system acts as a drainage network, carrying away extra fluid and proteins from tissues back into the bloodstream. If the lymphatic system is blocked or damaged, fluid collects in the tissues, leading to lymphedema.
This type of swelling is usually firm, non-pitting (does not leave a dent when pressed), and often affects one limb more than the other. Causes include cancers or tumors that press on lymph vessels, filariasis (a parasitic infection common in tropical countries), and complications after surgery or radiation therapy, particularly in breast cancer patients who have lymph nodes removed.
Some people may also have congenital lymphedema, where the lymphatic system does not form properly. Unlike other forms of edema, lymphatic obstruction often causes long-lasting swelling that does not respond well to diuretics.