Assessment of actinic skin damage by 20-MHz sonography

Ninety people were evaluated on age-related changes of the dermal connective tissue in light-exposed and protected skin areas non-invasively by 20-MHz sonography. The method allows sonographic structures to be measured and densitometric values to be quantified in a region of interest. Sonography of sun-exposed skin regions shows an echo-poor band in the upper dermis, which corresponds to actinic elastosis in the histological picture. The band is sharply demarcated from the entry echo. The border towards the non-actinically altered dermis below is often serrated. The sonographic phenomena can be explained by the micromorphological changes that develop in the upper dermis in actinic elastosis. An increased amount of elastic material and the destruction of the fiber architecture as well as an increase in ground substance and a mild inflammatory reaction cause a reduction in echogenicity. The extent of elastotic alterations and their progression is expressed in the densitometric values. These are low in areas of high sun exposure (the forehead and the infraorbital region). The echogenicity of the echolucent band (ELB) diminishes with increasing age. In highly exposed regions we found the lowest densitometric values already in the 41- to 50-year-olds. However, the width of the ELB remains relatively constant, extending in all locations to the middle dermis. This finding differs from earlier publications. On the buttock skin as a nonexposed area, an ELB could only be found in 6.7% of the cases.