Dermoscopic features of thin melanomas: a comparative study of melanoma in situ and invasive melanomas smaller than or equal to 1mm

BACKGROUND: Dermoscopy allows the early detection of melanomas. The preoperative determination of Breslow index by dermoscopy could be useful in planning the surgical approach and in selecting patients for sentinel lymph node biopsy. OBJECTIVES: This study aims at describing the dermoscopic features of thin melanomas and comparing melanomas in situ with invasive melanomas less than or equal to 1 mm thick. METHODS: This was an observational retrospective study in which the dermoscopy photographs of 41 thin melanomas were evaluated. Three observers evaluated together 14 dermoscopic criteria. RESULTS: Among thin melanomas, the most frequent criteria were presence of asymmetry in two axes in 95% of cases (39 cases), 3 or more colors in 80.4% of cases (33 cases), atypical dots or globules in 58.5% of cases (24 cases) and atypical network or streaks in 53.6% of cases (22 cases). The group of invasive melanomas presented with a higher frequency and statistical significance (p