Ultrasonographic subepidermal low-echogenic band, dependence of age and body site

The presence of an age-dependent subepidermal low-echogenic band (SLEB) is well established at specific body sites. Several studies have also proposed it to be a marker of photoaging, but only few studies have included children in their material, and UVR exposure has predominantly been evaluated as differences between body sites with different UVR exposure. The aim of this study was to further investigate the existence of SLEB and exploring its relation to both age and body site/UVR exposure.

In all 137 healthy volunteers from 4 to 68 years of age were included. In vivo high-frequency ultrasonography (B-mode, 20 MHz) was obtained from sun-exposed and sun-protected skin in a period with negligible environmental exposure to solar UVR. The SLEB was evaluated both visually and quantitatively.

We found a significant correlation between visual scoring of SLEB and dermal echogenicity, which supports the usefulness of SLEB scoring. We found that the grade (existence and development) of SLEB increased significantly with age at both the forehead and at the dorsal aspect of the forearm, where a well-defined SLEB was absent in children and present in over 50% of adults above the age of 40 years. No such age dependence was found either at the buttock or at the shoulder, and remarkably a well-defined SLEB was present in 37% of the adolescents at the buttock.

These results indicate that the age-related increase in SLEB grade at highly sun-exposed body sites might be attributed to UVR exposure. The presence of SLEB in both the young and at the sun-protected buttock points to a multifactorial etiology, where anatomical differences may play an important role as well as water content. SLEB might not be a very sensitive and specific marker of photoaging.