Unraveling Dermoscopic Distinctions in Actinic Keratosis: A Comparative Analysis

The diagnostic precision of dermoscopy in distinguishing between non-pigmented actinic keratosis (NPAK) and pigmented actinic keratosis (PAK) remains an area of ongoing research. This study aimed to scrutinize the reliability of dermoscopic markers in differentiating NPAK from PAK by examining 83 clinically identified AK cases, categorized into 45 NPAK and 38 PAK.

Methodology and Findings

The study, conducted at the Dermato-Oncology Unit of a Greek University Hospital, was ethically approved and involved informed consent from all participants. Clinical and dermoscopic evaluations were performed, with particular attention to established dermoscopic criteria such as the presence of pseudo-networks, scales,dermoscopy of actinic keratosis and specific vascular patterns. The intensity of pigmentation was quantified, and lesions were classified accordingly.

Statistical analysis revealed that the red pseudo-network was a significant feature for NPAK (p = 0.02), while the presence of a pigmented pseudo-network, especially with pigment intensity of over 10%, was highly indicative of PAK (p < 0.001). The pigmented pseudo-network demonstrated excellent diagnostic accuracy for PAK, with sensitivity and specificity rates of 89% and 77%, respectively.

Other features such as scale and widened follicular openings with yellowish dots were observed in both NPAK and PAK, but did not show statistical significance in differentiating the two. Similarly, linear wavy vessels and shiny streaks were more common in NPAK, while rosettes were more frequently observed in PAK; however, these findings were not statistically significant. The red starburst pattern was nearly statistically significant for PAK.

Discussion

The study found no significant differences between NPAK and PAK in terms of demographic factors such as age, gender, and Fitzpatrick skin type classification. However, PAK showed a tendency to occur in darker phototypes. The location of lesions on the scalp and face did not indicate a significant difference in the distribution between the two groups.

Dermoscopic examination provided valuable insights, particularly the pigmented pseudo-network, which was a strong predictor for PAK. The presence of a red pseudo-network was more prevalent in NPAK but did not offer discriminative potential. The study also noted that other dermoscopic features were equally distributed between the two types of AK and did not aid in differentiation.

The study concluded that pigmentation is the most reliable dermoscopic feature for differentiating NPAK from PAK. While other dermoscopic criteria are present in both types of AK, they do not provide significant differentiation. The presence of a pigmented pseudo-network, especially when pigment intensity exceeds 10%, is a key diagnostic indicator. The study acknowledges limitations, including a small sample size and potential bias, and calls for further research to expand the understanding of dermoscopic features in AK.