Evaluation of Skin Viscoelasticity in Breast Cancer-Related Lymphedema—Relationship with Subcutaneous Thickening and Fluid Retention

Background: Breast cancer-related lymphedema (BCRL) is associated with lymphatic fluid accumulation and subcutaneous tissue thickening, influencing the skin’s biomechanical properties. Although several studies have used the Cutometer® to assess skin elasticity in lymphedema, the relationship between viscoelastic parameters and subcutaneous fluid retention remains unclear. This study aimed to clarify how skin viscoelasticity relates to subcutaneous tissue thickening and fluid accumulation in patients with BCRL. Methods and Results: The study included 17 women who underwent unilateral breast cancer treatment and subsequently developed BCRL; 3-Tesla magnetic resonance imaging (MRI) system was used to confirm subcutaneous lymphedema. An ultrasound device was used to measure skin and subcutaneous tissue thickness, and Cutometer® was used to measure skin elasticity. Based on all measurement sites were categorized into the following three groups according to the presence or absence of lymphatic fluid accumulation, based on MRI results: with water, without water, and unaffected side. Among the 10 skin viscoelasticity parameters, significant differences were observed among the three groups for Ur (immediate retraction), Ur/Ue (net elasticity), and Ur/Uf (biological elasticity). Spearman’s rank correlation coefficient showed that Ur was not significantly correlated with skin thickness (ρ = 0.072, p = 0.56) or subcutaneous thickness (ρ = 0.197, p = 0.107). Conclusion: Ur was not significantly associated with tissue thickness, suggesting its sensitivity to lymphatic fluid accumulation. Ur may be a sensitive indicator for detecting subcutaneous fluid retention in BCRL. As a noninvasive parameter, it could complement current diagnostic tools and may be useful for longitudinal BCRL monitoring.