Dermoscopic predictors of melanoma in small diameter melanocytic lesions (mini‐melanoma): a retrospective multicentric study of 269 cases
Gianluca Nazzaro, Carlo Alberto Maronese, Giovanni Casazza, Serena Giacalone, Cristina Beatrice Spigariolo, Gabriele Roccuzzo, Gianluca Avallone, Stefania Guida, Gabriella Brancaccio, Paolo Broganelli, Giovanni Pellacani, Francesca Farnetani, Emanuela Passoni, Aimilios Lallas, Giuseppe Argenziano, Angelo Valerio Marzano
Abstract
BACKGROUND: Incidence of cutaneous melanoma is steadily growing, and its early recognition is of paramount importance. Small, pigmented lesions often represent a challenge for the clinician, as predictors of melanoma have not yet been uniquely identified in this setting. OBJECTIVES: To identify dermoscopic features that aid in distinguishing small diameter melanomas (≤5 mm) from equivocal melanocytic nevi measuring ≤5 mm. METHODS: A retrospective multicenter study was conducted to collect demographics, clinical and dermoscopic pictures of (i) histology-proven flat melanomas, measuring ≤5 mm, (ii) histology-proven but clinically/dermoscopically equivocal melanocytic nevi measuring ≤5 mm, and (iii) histology-proven flat melanomas, measuring >5 mm. An independent dermoscopic evaluation was performed. Differences in predefined dermoscopic features were assessed across the three groups. RESULTS: A total of 103 melanomas measuring ≤5 mm were collected; 166 control lesions, comprising 85 large (>5 mm) melanomas and 81 dubious, clinically equivocal melanocytic nevi measuring ≤5 mm were included. Of the 103 mini-melanomas, only 44 were melanoma in situ. Five dermoscopic predictors of melanoma were identified for the assessment of flat, non-facial melanocytic lesions measuring ≤5 mm, namely: atypical pigment network, blue-white veil, pseudopods, peripheral radial streaks, and presence of more than one color. The latter were combined into a predictive model capable of identifying melanoma with 65% sensitivity and 86.4% specificity, at a cut-off score of 3. Among melanomas measuring ≤5 mm, presence of a blue-white veil (P = 0.0027) or negative pigment network (P = 0.0063) was associated with invasiveness. CONCLUSION: A set of five dermoscopic predictors of melanoma, atypical pigment network, blue-white veil, pseudopods, peripheral radial streaks, and presence of more than one color is proposed for the assessment of flat, non-facial melanocytic lesions measuring ≤5 mm.