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 preoperativedetermination of Breslow index by dermoscopy could be useful in planning thesurgical approach and in selecting patients for sentinel lymph node biopsy.

OBJECTIVES

This study aims at describing the dermoscopic features of thin melanomas andcomparing melanomas in situ with invasive melanomas less than or equal to 1 mmthick.

METHODS

This was an observational retrospective study in which the dermoscopy photographsof 41 thin melanomas were evaluated. Three observers evaluated together 14dermoscopic criteria.

RESULTS

Among thin melanomas, the most frequent criteria were presence of asymmetry intwo axes in 95% of cases (39 cases), 3 or more colors in 80.4% of cases (33cases), atypical dots or globules in 58.5% of cases (24 cases) and atypicalnetwork or streaks in 53.6% of cases (22 cases). The group of invasive melanomaspresented with a higher frequency and statistical significance (p <0.05) 3 ormore colors (OR: 16.1), milky red areas (OR: 4.8) and blue-white veil (OR: 20.4),and a greater tendency to have streaks or atypical network (OR: 3.66).

CONCLUSIONS

Thin melanomas tend to have asymmetry in the two axes, 3 or more colors, atypicaldots or globules and atypical network or streaks. Melanomas in situ tend to haveup to 2 colors, no blue-white veil and no milky red area. Invasive melanomas tendto have 3 or more colors, a milky red area, blue-white veil, and atypical networkor streaks. Further studies are needed to confirm these findings.