Development of a Noninvasive Skin Evaluation Method for Lower Limb Lymphedema

The skin's condition is altered in lymphedema patients, and evaluating this change is important. Some noninvasive methods for evaluating skin condition have been reported, especially in upper limb lymphedema. However, evaluating the skin in lower limb lymphedema remains challenging and is often limited to palpation. We aimed to develop a noninvasive skin evaluation method for lower limb lymphedema patients. Twenty-five lower limb lymphedema patients were included. Skin induration and elasticity were measured using Indentometer^® IDM 400 and Cutometer^® MPA580. The relationship between the properties of skin from the healthy forearm and thigh, those of the affected thigh, and age was analyzed. Predicted skin induration age (IA) and elasticity age (EA) were calculated from the forearm, whereas actual values were calculated from the thigh, and the differences (ΔIA and ΔEA) were assessed. Patients were classified according to the International Society of Lymphology clinical staging system, and the differences in ΔIA and ΔEA were analyzed among the three groups (healthy, stage I/IIa, and stage IIb/III). Skin biopsy was performed in five unilateral lower limb lymphedema patients, and the dermal elastic fiber area was determined using microscopy with Elastica van Gieson staining. ΔEA significantly increased with disease progression, but ΔIA did not change significantly. Microscopy revealed elastic fiber filamentous changes, with decreased elastic fiber areas in lymphedema-affected skin. To our knowledge, this is the first report to evaluate lower limb skin elasticity in lymphedema quantitatively and noninvasively. ΔEA is useful for evaluating skin condition progression in lymphedema patients.