Heterogeneity in the Linear Shiny White Structures in Melanomas Seen With Polarized Light According to Histopathological Association: Cross-sectional Observational Study in 118 Cutaneous Melanomas

Polarized dermoscopy enables visualization of linear shiny white structures in melanomas, thought to be due to the existence of fibrosis in the dermis. Our objective was to establish the existence of two types of linear shiny white structures and assess their association with different histological structures. We performed a cross-sectional study including all non-acral, non-facial melanomas from our hospital with linear shiny white structures. The outcome variable was the type of linear shiny white structures: shiny white streaks and white strands. We evaluated their association with explanatory variables that may affect the reflectance of melanomas and Breslow index. We used χ2 statistics and also calculated the sensitivity and specificity of each linear shiny white structure to predict those variables. We detected linear shiny white structures in 118 melanomas. Regarding shiny white streaks, we only found a statistically significant positive relationship with fibrosis in the papillary dermis. Regarding white strands, we found statistically significant and positive relationships with hyperkeratosis, Breslow index of 0.8 mm or more and acanthosis. Sensitivity and specificity study revealed that the presence of shiny white streaks was the most sensitive (81.7%) and specific (72.3%) for fibrosis in the papillary dermis, and presence of white strands was the most sensitive (91.1%) and specific (85.7%) for hyperkeratosis.