Dermoscopic Features of Facial Pigmented Skin Lesions

Four types of facial pigmented skin lesions (FPSLs) constitute diagnostic challenge to dermatologists; early seborrheic keratosis (SK), pigmented actinic keratosis (AK), lentigo maligna (LM), and solar lentigo (SL). A retrospective analysis of dermoscopic images of histopathologically diagnosed clinically-challenging 64 flat FPSLs was conducted to establish the dermoscopic findings corresponding to each of SK, pigmented AK, LM, and SL. Four main dermoscopic features were evaluated: sharp demarcation, pigment pattern, follicular/epidermal pattern, and vascular pattern. In SK, the most specific dermoscopic features are follicular/epidermal pattern (cerebriform pattern; 100% of lesions, milia-like cysts; 50%, and comedo-like openings; 37.50%), and sharp demarcation (54.17%). AK and LM showed a composite characteristic pattern named “strawberry pattern” in 41.18% and 25% of lesions respectively, characterized by a background erythema and red pseudo-network, associated with prominent follicular openings surrounded by a white halo. However, in LM “strawberry pattern” is widely covered by psewdonetwork (87.5%), homogenous structureless pigmentation (75%) and other vascular patterns. In SL, structureless homogenous pigmentation was recognized in all lesions (100%). From the above mentioned data, we developed an algorithm to guide in dermoscopic features of FPSLs. 1. Introduction Until now, almost only melanocytic lesions selected on the basis of their clinical atypia or which appear equivocal on naked eye examination have been shown to benefit from the use of dermoscopy. In our experience, dermoscopic evaluation of pigmented lesions located on the face may require a different approach, as many of them are nonmelanocytic in nature. Moreover, at this site, dermoscopy reveals specific criteria according to the particular histological architecture shown by sun-damaged skin [1]. For example, under dermoscopy, the presence of a pseudonetwork is characteristic of pigmented nonmelanocyte lesions on the face. This feature may not be related to the rete ridges of the epidermis—which are absent or blunted due to the anatomy of the skin in this area and to photoaging—but is due to the interruption of the homogeneous pigmentation by the openings of hair follicle ostia and adnexal structures [2]. Hence, four types of facial pigmented skin lesions (FPSLs) constitute diagnostic challenge to dermatologists, namely, early seborrheic keratosis (SK), pigmented actinic keratosis (AK), lentigo maligna (LM), and solar lentigo (SL). We aimed to analyze the dermoscopic patterns of