Non-polarized dermoscopy (NPD) | Polarized dermoscopy (PD) | |
Technique | Requires direct contact between the scope and the skin. Requires a liquid interface. | Although PD can be used in either the contact or non-contact mode, and can be used with or without a liquid interface, using a liquid interface and direct contact provides superior image clarity. |
Skin layers | Superficial layers are better visualized than deeper layers. | Deep layers of epidermis and papillary dermis (depth of polarized light ~60 to 100 micrometers) are better visualized than superficial layers. |
Colors and structures | Blue white-veil due to orthokeratosis is more conspicuous. | Pink and red colors are more conspicuous. |
Milia-like cysts and comedo-like structures are easier to recognize under NPD. | Milia-like cysts and comedo-like structures are less conspicuous with PD. | |
The steel-blue color seen in blue nevi appears more homogeneous under NPD. | The blue color in blue nevi will appear darker with differing hues. | |
Regression areas (peppering, blue white areas and gray color) are more conspicuous with NPD. This difference is especially pronounced on thin skin such as facial or sun-damaged skin. | The white scar-like areas are more conspicuous under PD. | |
The ability to visualize vascular structures is dependent upon the amount of pressure applied to the skin. | Vascular structures and collagen are more conspicuous. | |
Shiny white structures, including white shiny streaks, also known as crystalline structures, are only seen under PD. |
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