Dermoscopic rosettes as a clue for pigmented incipient melanoma.

The rosette structure is a dermoscopic sign visible under polarized light, characterized by 4 white points arranged as a 4-leaf clover. It has been mainly described in facial sun-damaged skin and actinic keratosis, although it has also been found in squamous and basal cell carcinomas, and in 2 cases of hypomelanotic melanomas. We describe 2 different cases of pigmented incipient melanomas with the presence of multiple rosettes and shiny white structures on dermoscopy. In the reflectance confocal microscope they exhibit a disarranged epidermal architecture with atypical and dendritic cells. Histological examination showed focal hyperkeratosis and a normal corneal layer presented alternatively. To our knowledge this is the first description of rosette structures in pigmented melanomas. Based on a proper dermoscopic- confocal-histopathological correlation, we hypothesize that rosettes could correspond to optic phenomena due to changes in the superficial epidermal reaction and in the acrosyringia.