The current best practice is a three-stage classification consensus guideline as published by the International Society of Lymphology (ISL). Severity of lymphedema is however not only determined by presence of pitting (which is the phenomenon when the swollen area has a dimple (or pit) after you press it for 5 to 10 seconds) and presence of adipose tissue or not, but is also determined by the volume of the edema, a quantification of the condition of the skin and the location/expansion of the edema over the body. Currently a severity score considering these different aspects does not exist. Although there is consensus that the ISL staging systems is a necessary part of the diagnosis of lymphedema, it gives not enough information about the severity of the lymphedema. A more detailed and comprehensive classification system applicable for primary and secondary lymphedema and considering multiple edema characteristics, remains to be formulated.

The researchers objective in this study is to develop a diagnostic set, including a 'severity score', for patients with LLL.

Inclusion Criteria:

Patient group

• Unilateral or bilateral, primary or secondary LLL
• Objective diagnosis of lymphedema: ≥ 5% volume difference between both legs OR ≥ 2 minor/ 1 major criteria on lymphoscintigraphy OR presence of ICG dermal backflow
• Age ≥ 18 years
• Able to read, understand and speak Dutch

Healthy controls

- Age, gender & BMI-matched healthy controls

Exclusion Criteria:

• Pregnant participants
• Presence of chronic venous insufficiency C4, C5, C6; deep venous thrombosis; post-thrombotic syndrome
• Presence of skin infections of wounds at the level of the lower limbs at the moment of inclusion

Patients with LLL will be recruited in the center for lymphedema in UH Leuven in Belgium and in the center for lymphedema in Nij Smellinghe Hospital in Drachten in the Netherlands.

Healthy volunteers, both in Belgium as well as in the Netherlands.