Shiny white structures
Shiny white structures
Shiny white structures (SWS) are only seen with polarized dermoscopy and may require the operator to rotate the dermatoscope over the lesion to see them (angular dependence). SWS include shiny white lines (synonym=streaks), shiny white blotches, strands, areas, and rosettes.
Shiny white lines, chrysalis structures or crystalline structures?
Shiny white lines are white lines oriented orthogonally, parallel or perpendicularly to each other (Kittler et al., 2016a). Histologically, they correlate to stromal alteration and fibrosis (increased dermal collagen), and are secondary to the birefringent properties of collagen bundles (Pizzichetta et al., 2014). Shiny white streaks can be observed in melanomas, atypical genital nevi, Spitz nevi, and LPLKs (Pizzichetta et al., 2014; Shitara et al., 2014). They also correlate with dermal invasion in cases of melanoma (Balagula et al., 2012).
The metaphorical term ‘chrysalis structure’ has previously been used in the dermoscopic literature to describe the bright shiny white lines, which are often arranged in an orthogonal distribution. However, it was recently noted that the term chrysalis is a misnomer, and a suggestion was made to change the terminology to ‘crystalline’ structure. Images of wax moth cocoons reminded some of these shiny white lines as the cocoons also aligned them- selves in a parallel and orthogonal orientation and appeared as short tapered lines. Dr James Grichnick, who studied entomology, and Dr Harald Kittler subsequently noted that the term ‘chrysalis’ actually refers to the pupae of the butterfly and not that of a moth; the moth has a cocoon, and the butterfly has a chrysalis. The chrysalis of a butterfly does not look like the shiny white lines seen with dermoscopy. Changing the name of these white lines to ‘cocoon structures’ to reflect the true meanings of the terms, did not appeal to anyone. Dr James Grichnik strongly recommended changing the name to ‘crystalline’, as it still captures the essence of the structure: whitish linear and orthogonal lines. Lastly, these structures are visible with polarized light, but are transparent with non-polarized light, which further reinforces the value of using the term ‘crystalline’; while crystal is transparent, colour can indeed be revealed under different light conditions. (Liebman et al., 2012)
An example of shiny white lines as they appear in polarized (right image) as opposed to non-polarized dermoscopy (left image):
Shiny white blotches and strands
Shiny white blotches are small to large white homogenous areas. Strands are parallel and linear white areas that usually do not intersect (Liebman et al., 2012). The exact histopathological correlate is unknown, but they seem to correspond to dermal fibrosis. The combined presence of shiny white blotches and strands is associated with a high diagnostic specificity for nonpigmented BCC (Navarrete-Dechent et al., 2016).
Shiny white areas
White shiny areas are characterized as white shiny clods or larger structureless areas with a shiny, bright white colour (Liebman et al., 2012)
Rosettes
Rosettes (also known as ‘four-clod dots’) are defined as four white points, arranged as a four leaf clover. They are not lesion-specific and are described in many tumoral and inflammatory lesions, including: scars, dermatofibroma, actinic keratosis, squamous cell carcinoma and melanoma and more. Smaller rosettes are mainly caused by polarizing horny material at infundibular level in adnexal openings and larger rosettes mainly by concentric perifollicular fibrosis [1].
