Dermoscopy of Actinic Keratosis: Is There a True Differentiation between Non-Pigmented and Pigmented Lesions?

Abstract

Dermoscopic features of actinic keratosis (AK) have been widely studied, but there is still little evidence for their diagnostic accuracy. Our study investigates whether established dermoscopic criteria are reliable predictors in differentiating non-pigmented actinic keratosis (NPAK) from pigmented actinic keratosis (PAK). For this purpose, dermoscopic images of 83 clinically diagnosed AK (45 NPAK, 38PAK) were examined, and the sensitivity (Se), specificity (Sp), positive predictive value (PPV), and negative predictive value (NPV) were assessed. Features with statistical significance were the red pseudo-network (p = 0.02) for NPAK and the pigmented pseudo-network (p < 0.001) with a pigment intensity value even less than 10% for PAK (p = 0.001). Pigmented pseudo-network (Se: 89%, Sp: 77%, PPV: 77%, NPV: 89%) with a pigment intensity value of more than 10% (Se: 90%, Sp: 86%, PPV: 79%, NPV: 93%) had excellent diagnostic accuracy for PAK. Scale and widened follicular openings with yellowish dots surrounded by white circles were equally represented in both variants of AK. Linear wavy vessels and shiny streaks were more prominently observed in NPAK, as were rosettes in PAK, but these results failed to meet statistical significance. The red starburst pattern was near statistical significance for PAK. Therefore, pigmentation is the strongest dermoscopic predictor for the differentiation between NPAK and PAK.

Keywords: dermoscopy; non-pigmented actinic keratosis; pigmented actinic keratosis; skin tumors.

Figure 1

(a) A 67-year-old male patient with a pigmented scaly plaque on the left lateral side of the face. (b) Pigmented pseudo-network and widened follicular openings along with fine scaling demonstrate a typical pigmented actinic keratosis of the face. (c) A 62-year-old female patient with a pink, slightly elevated plaque on the nose. (d) A red pseudo-network surrounding widened follicular ostia and yellowish dots are features of a non-pigmented actinic keratosis. Linear wavy vessels can also be observed.