# A Closer Look at Dowling-Degos Disease: A Case Report and Quantitative Assessment of Its Surface Texture Parameters

## TL;DR

This paper uses 3D surface metrology to describe the unique skin texture of Dowling-Degos disease, offering a potential noninvasive diagnostic tool.

## Contribution

The study introduces quantitative surface texture analysis of Dowling-Degos disease using 3D metrology, a novel approach for this condition.

## Key findings

- DDD skin showed increased roughness and irregularity compared to unaffected skin.
- DDD surface texture differs from psoriatic lesions with lower mean roughness.
- Surface metrology can provide a quantitative profile for DDD diagnosis and monitoring.

## Abstract

Dowling-Degos disease (DDD) is a rare genodermatosis characterized by reticulated hyperpigmented macules and papules, yet its surface architecture has not been quantitatively described. In this case, we utilized 3D surface metrology to objectively characterize its surface texture. A shave biopsy from the inner thigh of a 54-year-old woman with clinically and histopathologically confirmed DDD was scanned using the S Neox optical profiler (Sensofar, Barcelona, Spain) at 20x and 50x magnification. Roughness parameters, including mean roughness (Sa), maximum surface height (Sz), maximum valley depth (Sv), maximum peak height (Sp), root mean square roughness (Sq), skewness (Ssk), and sharpness (Sku), were extracted and compared with previously published values for both unaffected and psoriatic skin. When compared to unaffected skin, DDD showed markedly increased Sa, Sz, and Sv, indicating a more irregular and deeply sculpted skin surface. In contrast to psoriatic lesions, DDD demonstrated lower Sa. Between magnifications, Sp was significantly greater in the 20x scan. These findings indicate that DDD has a distinct topographic profile that could support noninvasive diagnosis and monitoring. Surface metrology may complement clinical, dermoscopic, and histopathologic evaluation by providing a quantitative description of disease-specific skin texture.