Non polarized dermoscopy

From dermoscopedia

Main PagePrinciples of dermoscopyNon polarized dermoscopy
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 Editor: Alon Scope

 Author(s): Florentia Dimitriou     ·  Alon Scope     ·  Ashfaq A. Marghoob
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Description Describes the principleThis glossary term has not yet been described. 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. using non polarized lightThis glossary term has not yet been described. also known als standard dermoscopy
Author(s) Florentia Dimitriou · Alon Scope · Ashfaq A. Marghoob
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Status released
Status update July 11, 2018
Status by Ralph P. Braun


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Non polarizied dermoscopes

A dermoscope (or 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.) is a handheld deviceA piece of equipment designed to perform a special function, equipped with a magnification lens and a light source. It enables the visualization of the subsurface morphologyThis glossary term has not yet been described. of cutaneous lesions, down to the depth of the superficialThis glossary term has not yet been described. dermis.It reveals colorsThis glossary term has not yet been described. and structuresThis glossary term has not yet been described. that are normally not visible to the unaided eye and improves the diagnostic accuracyThis glossary term has not yet been described. and confidence level of experienced users, for both pigmented and non-pigmentedThis glossary term has not yet been described. skin lesions.
Non-polarized dermoscopes (NPD) are equipped with a magnification lens and light-emitting diodes to provide illumination. They require direct contact of the glass plate with the skin surface, and the presence of a liquid interface with a refractive indexA dimensionless number that describes how light propagates through a medium equal to or closely matching that of the skinThis glossary term has not yet been described.. Different immersionThis glossary term has not yet been described. liquids can be used: 70% alcohol, gel (i.e., ultrasound gel, antibacterial gel), water or mineral oil. Air bubbles between the dermoscope’s glass plate, the immersion liquid, and the skin surface create a skin–air interface. The interface causes back-scatter of light and precludes the observer from visualizing structures below the stratum corneum. Thus, air bubbles should be eliminated.
NPD allow visualization of subsurface structures located in the epidermis and the dermal-epidermal junction (DEJ), but can hardly visualize structures deeper than the DEJ.



NPD optics principles

Optical properties of light during the use of NPD

  • The Surface glareDifficulty seeing in the presence of light that is reflected from the skin surface is eliminated by matching the refractive indexes of the NPD's glass plate, the immersion medium, and the skin.
  • SuperficialThis glossary term has not yet been described. penetrating light is the main source of contrast when using NPD. The light that enters the skin is absorbed (e.g. by melanin) or reflected back (e.g. by keratin in milia-like cystsThis glossary term has not yet been described.) at the layers of the epidermis and the DEJ. The superficial penetrating light undergoes minimal scattering events and is therefore the main source of light that reflects back to the NPD lens.
  • Deep penetrating light contributes only a small fraction of back-reflected light detected with NPD. This is due to the decay of light by multiple scattering events, as it goes deeper into the skin.


MelanomaThis glossary term has not yet been described., as it appears clinically (insert) and on NPD:


Fig. 1 seven-point checklist.jpg

Globular nevus as it appears clinically (insert) and on NPD:

Globules.jpg



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 lightThis glossary term has not yet been described. 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.
  8. Kelly, S.C. & Purcell, S.M., 2006, Prevention of nosocomial infectionThis glossary term has not yet been described. during dermoscopy? Dermatol Surg, 32, 552–5.
  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 nail pigmentation. Arch Derma- tol, 138, 1327–33.
  15. Stauffer, F., Kittler, H., Forstinger, C. & Binder, M., 2001, The dermatoscope: 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 accuracy and confidence level: a pilot study. Dermatol Surg, 34, 1389–95.