Significance of Ultrasound Examination of Skin and Subcutaneous Tissue in Secondary Lower Extremity Lymphedema

OBJECTIVES: To clarify whether ultrasound findings of skin and subcutaneous tissue represent the severity of lymphedema. MATERIALS AND METHODS: Thirty-five patients with secondary lower extremity lymphedema caused by intrapelvic lymph node dissection during cancer surgery, who first visited our clinic between April 2009 and March 2012, were studied retrospectively. At their first visit, skin thickness, subcutaneous tissue thickness, and subcutaneous echogenicity were assessed at 8 points on the thigh and leg of both legs using an 11-MHz ultrasound transducer. These findings correlated with the International Society of Lymphology (ISL) clinical stage. RESULTS: Skin thickness, subcutaneous tissue thickness, and subcutaneous echogenicity all showed significant positive correlation with the ISL stage. However, measuring skin and subcutaneous tissue thicknesses was not feasible in 29%-71% of scanning points in stage III legs because of poor delineation of boundaries at the dermo-hypodermal junction and the upper boundary of the muscular fascia. However, subcutaneous echogenicity was assessable at all scanning points and was linearly correlated with ISL stage. CONCLUSION: Evaluating subcutaneous echogenicity is feasible even with low-resolution ultrasound and reflects the ISL stage. These findings may thus be valuable to objectively represent the severity of extremity lymphedema.