Polarized dermoscopy

From dermoscopedia

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 Authored by: Florentia Dimitriou     ·  Alon Scope     ·  Ralph P. Braun

 Keywords:   polarized light · dermoscopy
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Description Explains the principleThis glossary term has not yet been described. of polarized lightThis glossary term has not yet been described. dermoscopyThe examination of [skin lesions] with a 'dermatoscope'. This traditionally consists of a magnifier (typically x10), a non-polarised light source, a transparent plate and a liquid medium between the instrument and the skin, and allows inspection of skin lesions unobstructed by skin surface reflections. Modern dermatoscopes dispense with the use of liquid medium and instead use polarised light to cancel out skin surface reflections.
Author(s) Florentia Dimitriou · Alon Scope · Ralph P. Braun
Owner Ralph Braun→ send e-mail
Status released
Status update July 2, 2018
Status by Ralph P. Braun


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Polarized dermoscopes

Polarized dermoscopes (PD), like non-polarized dermoscopes, contain light-emitting diodes to provide illumination and are equipped with a magnification lens. However, PDs use two polarized filters to achieve cross-polarization (see below). Hence, they do not require direct contact with the skinThis glossary term has not yet been described., and do not require the use of immersionThis glossary term has not yet been described. liquids.
PD allow visualization of subsurface structuresThis glossary term has not yet been described. located at the dermal-epidermal junction (DEJ) or superficialThis glossary term has not yet been described. dermis, and they are nearly "blind" to the skin's surface and to structures in the superficial epidermis (e.g., comedo-like openings).
Some PD devices allow the user to opt between non-contact PD and contact PD. Under contact PD, the use of an immersion fluid (e.g. 70% alcohol) can enhance image quality, probably by allowing more source light to enter through the stratum corneum.

Optical properties of light during the use of PD

  • Light emitted from the dermoscopy unit (source) passes through a polarizer, resulting in the generation of polarized (unidirectional) light.
  • Light reflecting back toward our eye (detector) must first pass through a cross-polarized filter whose direction is perpendicular (orthogonal) to that of the source polarizer.
  • Polarized lightThis glossary term has not yet been described. cannot pass through the cross-polarizing filter unless the light changes its direction by 90°, which occurs if the original polarized light undergoes sufficient scattering events in the skin that change its direction ("randomization of polarization").
  • Surface glareDifficulty seeing in the presence of light that is reflected from the skin surface: maintains its original polarization, and thus cannot pass through the cross-polarized filter. Therefore, PD is "blind" to surface glareDifficulty seeing in the presence of light that is reflected from the skin surface.
  • SuperficialThis glossary term has not yet been described. light: does not undergo enough scattering events to result in randomization of polarization. Therefore, PD is also "blind" to back-reflected light from the superficial layers of the epidermis.
  • Deep penetrating light: reaches the level of the DEJ and superficial dermis, undergoing multiple scattering events that result in randomization of polarization. Thus, back-reflected "deep penetrating light" can pass through the cross-polarization filter and enter our eye, allowing the visualization of dermoscopic structuresThis glossary term has not yet been described. from the DEJ and superficial dermis.

PD optics

Shiny white streaks, a feature only visible on PD:

Shiny white streaks.jpg




ImagesA representation of a person, animal or thing, photographed, painted or otherwise made visible. for keyword "shiny white streakslines white perpendicular*"





ReferencesThis is material contained in a footnote or bibliography holding further information.

  1. An Atlas of DermoscopyThe examination of [skin lesions] with a 'dermatoscope'. This traditionally consists of a magnifier (typically x10), a non-polarised light source, a transparent plate and a liquid medium between the instrument and the skin, and allows inspection of skin lesions unobstructed by skin surface reflections. Modern dermatoscopes dispense with the use of liquid medium and instead use polarised light to cancel out skin surface reflections., Second Edition. Marghoob A. et al. CRC Press; 2012.
  2. Agero, A.L., Taliercio, S., Dusza, S.W., Salaro, C., Chu, P. & Marghoob, A.A., 2006, Conventional and polarized dermoscopy features of dermatofibromaDermatofibromas are hard solitary slow-growing papules (rounded bumps) that may appear in a variety of colours, usually brownish to tan; they are often elevated or pedunculated. A dermatofibroma is associated with the dimple sign; by applying lateral pressure, there is a central depression of the dermatofibroma.. Arch Dermatol, 142, 1431–7.
  3. Anderson, R.R. & Parrish, J.A., 1981, The optics of human skin. J Invest Dermatol, 77, 13–19.
  4. Bafounta, M.L., Beauchet, A., Aegerter, P. & Saiag, P., 2001, Is dermoscopy (epilumi- nescence microscopy) useful for the diagnosisis the identification of the nature and cause of a certain phenomenon. Diagnosis is used in many different disciplines with variations in the use of logic, analytics, and experience to determine "cause and effect". In systems engineering and computer science, it is typically used to determine the causes of symptoms, mitigations, and solutions of melanomaThis glossary term has not yet been described.? Results of a meta- analysis using techniques adapted to the evaluation of diagnostic tests. Arch Dermatol, 137, 1343–50.
  5. Benvenuto-Andrade, C., Dusza, S.W., Agero, A.L., Scope, A., Rajadhyaksha, M., Halpern, A.C. & Marghoob, A.A., 2007, Differences between polarized light der- moscopy and immersion contact dermoscopy for the evaluation of skin lesions. Arch Dermatol, 143, 329–38.
  6. Benvenuto-Andrade, C., Dusza, S.W., Hay, J.L., Agero, A.L., Halpern, A.C., Kopf, A.W. & Marghoob, A.A., 2006, Level of confidence in diagnosis: clinical examinationThis glossary term has not yet been described. versus dermoscopy examination. Dermatol Surg, 32, 738–44.
  7. Gewirtzman, A.J., Saurat, J.H. & Braun, R.P., 2003, An evaluation of dermoscopy fluids and application techniques. Br J Dermatol, 149, 59–63.
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  9. Kittler, H., Pehamberger, H., Wolff, K. & Binder, M., 2002, Diagnostic accuracyThis glossary term has not yet been described. of dermoscopy. Lancet Oncol, 3, 159–65.
  10. MacKie, R.M., 1971, An aid to the preoperative assessment of pigmented lesions of the skin. Br J Dermatol, 85, 232–8.
  11. MacKie, R.M., 1972, Cutaneous microscopy in vivo as an aid to preoperative assessment of pigmented lesions of the skin. Br J Plast Surg, 25, 123–9.
  12. Marghoob, A.A., Cowell, L., Kopf, A.W. & Scope, A., 2009, Observation of chrysalis structuresolt term for Chrysalis / Cristalline Structures with polarized dermoscopy. Arch Dermatol, 145, 618.
  13. Pan, Y., Gareau, D.S., Scope, A., Rajadhyaksha, M., Mullani, N.A. & Marghoob, A.A., 2008, Polarized and nonpolarized dermoscopy: the explanation for the observed differences. Arch Dermatol, 144, 828–9.
  14. Ronger, S., Touzet, S., Ligeron, C., Balme, B., Viallard, A.M., Barrut, D., Colin, C. & Thomas, L., 2002, Dermoscopic examination of nailThis glossary term has not yet been described. pigmentation. Arch Derma- tol, 138, 1327–33.
  15. Stauffer, F., Kittler, H., Forstinger, C. & Binder, M., 2001, The dermatoscopeThis traditionally consists of a magnifier (typically x10), a non-polarised light source, a transparent plate and a liquid medium between the instrument and the skin, and allows inspection of skin lesions unobstructed by skin surface reflections. Modern dermatoscopes dispense with the use of liquid medium and instead use polarised light to cancel out skin surface reflections.: a potential source of nosocomial infection? Melanoma Res, 11, 153–6.
  16. Wang, S.Q., Dusza, S.W., Scope, A., Braun, R.P., Kopf, A.W. & Marghoob, A.A., 2008, Differences in dermoscopic imagesA representation of a person, animal or thing, photographed, painted or otherwise made visible. from nonpolarized dermoscope and polarized dermoscope influence the diagnostic accuracyThis glossary term has not yet been described. and confidence level: a pilot study. Dermatol Surg, 34, 1389–95.