A novel approach to measuring skin elasticity in systemic sclerosis: results from a pilot study

Methods for objective assessment of skin involvement in systemic sclerosis

PURPOSE OF REVIEW

Skin fibrosis is the most prominent disease manifestation of systemic sclerosis (SSc). Although the treatment for other SSc manifestations has expanded over the years, there is limited progress in identifying effective treatment options for SSc skin involvement. This is in part due to limitations in the utilized outcome measures for assessment of skin fibrosis. This review focuses on different emerging assessment tools for SSc skin involvement and their potential use for clinical care and multicenter trials.

RECENT FINDINGS

Durometer and other device-based methodologies requiring application of direct pressure to the affected skin have been studied in SSc. However, there are concerns that the required application of pressure might be a source of variability. Ultrasound-based methods have been compared with modified Rodnan Skin Score in several studies, indicating acceptable construct validity. However, few studies have examined their criterion validity by providing comparisons to skin histology. Optical coherence-based methods show promising preliminary results for simultaneous assessment of skin fibrosis and vasculopathy. Further standardization and validation (including comparison to skin histology) of these promising novel assessment tools in large, longitudinal SSc cohort studies are needed to establish them as clinically useful outcome measures with acceptable sensitivity to change.

SUMMARY

Recent advances in imaging techniques provide a promising opportunity for development of a valid and reliable assessment tool for quantification of SSc skin fibrosis, which can pave the way for approval of effective treatment options for this high burden disease manifestation.

Truncated Hollow Cone Probe for Assessing Transepidermal Water Loss and Skin Hardness

This study proposes a skin analysis device using a truncate hollow cone (THC) probe for measuring both transepidermal water loss (TEWL) and skin hardness. Because skin health is closely related to the epidermal barrier function and skin mechanical property, it is important to measure their biophysical indicators at the same time, to understand skin conditions and diagnose skin disorders such as atopic dermatitis and systemic sclerosis. Previous skin analyzers, however, required different probes with different protocols for each biophysical indicators, which makes the measurement inconvenient and increases the measurement uncertainty. The present device consists of a THC probe equipped with humidity and force sensors, and an actuator that simultaneously measure both TEWL and skin hardness which indicate the integrity of the epidermal barrier function and the skin mechanical property, respectively. Using artificial reference skins, the prototype device showed the TEWL with a sensitivity and linearity of 0.011 (%/s)/(g/m²/h) and 99.5%, and the hardness with 0.075 N/(Shore 00) and 97.6%, respectively, which are within the appropriate range for the properties of human skin. The on-body measurement of five subjects showed that the proposed device could measure both the TEWL and skin hardness without any crosstalk from each other. The proposed device has great potential for in-depth analysis of the health status of the skin which could indicate various skin diseases.