P059 Dermoscopy of naevoid melanoma: a comparative analysis of shared diagnostic features in histologically confirmed cases

Abstract

Naevoid melanoma is a well-recognized diagnostic pitfall, often mimicking benign melanocytic naevi on both clinical and dermoscopic examination. Its deceptively benign appearance can lead to delayed diagnosis and potential adverse clinical outcomes. Improved characterization of recurring dermoscopic features may enhance early recognition and diagnostic accuracy. Our aims were to identify common dermoscopic features in a series of histologically confirmed naevoid melanomas and to describe distinguishing patterns that might aid differentiation from benign melanocytic naevi. Five dermoscopic images of histologically confirmed naevoid melanomas were analysed. Images were contributed by multiple clinicians and acquired using a range of dermatoscopes, including polarized and nonpolarized modalities, reflecting real-world clinical practice. A qualitative, descriptive dermoscopic assessment was performed, focusing on global architecture, pigment patterns, colour variegation, vascular structures, regression features and symmetry. Dermoscopic features were compared across lesions to identify recurring patterns of potential diagnostic relevance. Despite heterogeneity in image acquisition and lesion appearance, all cases exhibited a deceptively benign global morphology with internal dermoscopic asymmetry. Common features included absence or disruption of a typical pigment network, presence of structureless areas, colour variegation (comprising combinations of brown, grey, blue, pink and white) and irregular or polymorphous vascular patterns. Shiny white streaks and subtle regression structures were observed in several lesions. In contrast to benign intradermal or compound naevi, peripheral clods or globules – when present – were irregular in size and distribution, and lesion margins were frequently ill defined. Naevoid melanoma presents with an overall naevus-like architecture, while harbouring subtle but consistent dermoscopic indications of malignancy. Internal asymmetry, structureless pigmentation, colour variegation, atypical vascular patterns and regression-related features appear to be recurring hallmarks. Recognition of these shared features may improve diagnostic confidence and reduce missed or delayed diagnoses of this challenging melanoma subtype.