Subcutaneous tissue ultrasonography in legs with dependent edema and secondary lymphedema

To elucidate the differences in subcutaneous ultrasound findings between dependent edema (DE) and secondary lower extremity lymphedema (LE).

Twenty legs in 10 patients with DE and 54 legs in 35 patients with LE, who first visited our clinic between April 2009 and December 2012, were studied retrospectively. Subcutaneous echogenicity and echo-free space (EFS) were assessed at 8 points on the thigh and leg using an 8-12 MHz ultrasound transducer.

In DE, echogenicity was increased most in the lower leg, without a difference between the medial and lateral side. The EFS was most remarkable in the lower leg, and the lateral side was more severe. In the early stages of LE, echogenicity was similarly increased in the medial thigh and in the leg, while remarkable EFS was observed only in the lower leg. As clinical severity progressed, echogenicity increased in all parts of the lower extremity. EFS also increased in all parts of the leg, but the lower leg was still the most severe.

Echogenicity seemed to progress differently in DE and LE, but EFS progressed similarly and according to gravity. The current ultrasound findings may have added some diagnostic value in differentiating these conditions.