Blue Nevus With Rosettes on Polarized Light Dermoscopy

摘要

Rosettes are shiny white structures consisting of 4 white dots, similar to a 4-leaf clover. In dermoscopy, they can be seen with polarized light because of an optical phenomenon. Small rosettes (0.1–0.2 mm) are associated with the presence of concentric keratin at the infundibular level of the annex openings, the largest (0.3–0.5 mm) with perifollicular concentric fibrosis. When multiple rosettes are present, they are usually oriented at the same angle. They have been reported mainly related to actinic keratosis and squamous cell carcinoma. Nevertheless, they are not specific to any condition, as they have been described in a number of inflammatory and tumoral cutaneous lesions, including melanoma [ ]. The latter is one of the main differential diagnoses of blue nevi.