Supervised by: dr. Stephen Akihito Wirya, MS, RCPSC-UK, Sp.DV
In this post, we are going to discuss about the pink part of Dermapamine’s logo and the thing Derma’s holding on her right hand. A tool to help dermatologists differentiate between benign and malignant lesions. The Dermatoscope and Dermoscopy.
A dermatoscope functionally simulates a magnifying lens, with the added features of much higher magnification, and an adjustable inbuilt illuminating system. Dermatoscopes may be with or without an in-built image capturing facilities.
Dermatoscopes come in all shapes an sizes, with polarized and/or nonpolarized light sources.
Some dermatoscopes can also be attached to camera or smartphone.
In dermatology daily practice, dermatoscope is often used for dermoscopy. What is dermoscopy?
Dermoscopy, also known as dermatoscopy, epiluminescence microscopy, or skin surface microscopy is a non- invasive, in-vivo technique that has traditionally been useful for the evaluation of suspicious skin lesions.
Dermoscopy can help identify lesions and differentiate melanocytic lesions from dysplastic lesions, melanomas, or non-melanoma skin cancers such as basal cell carcinoma or squamous cell carcinoma.
The use of dermoscopy has also expanded to include utilization for diagnosis of dermatological disorders including inflammatory dermatosis, pigmentary dermatosis, infectious dermatosis, and disorders of the hair, scalp, and nails.
The basic principle of dermoscopy is transillumination of a lesion in order to study it with high magnification to visualize subtle features.
There are 3 modes of dermoscopy:
1. nonpolarized contact dermoscopy
2. polarized contact dermoscopy
3. polarized non-contact dermoscopy
Dermatoscopes with nonpolarized light require direct skin contact and a liquid interface (eg, alcohol, ECG/USG gel, mineral oil, liquid paraffin) between the scope’s glass plate and the skin for the visualization of subsurface structures. Dermatoscopes with polarized light do not require direct skin contact or a liquid interface; however, contacting the skin and using a liquid interface will provide a sharper image.
The essential components of a dermatoscope include:
1) A set of achromatic lenses with magnification starting from 10× up to 200× or even higher,
2) An inbuilt illuminating system composed of halogen lamps placed within the handheld piece,
3) A source of power supply such as rechargeable or replaceable batteries or rechargeable handles.
When light is incident on the skin (thick red arrow), most of it tends to get reflected back (thin red arrow), while the remaining gets refracted (oblique orange arrow), diffracted (yellow shooting arrows) or absorbed (crimson area). On looking directly at the skin by unassisted eyes, one sees the external image of the skin formed by the reflected light.
The picture above is showing the working principle of a modern dermoscope.
In the polarized mode, the light from the dermoscope gets polarized by two cross-polarizers, cutting out the scattered light reflected from the skin, and allowing an image formation with visualization of sub-stratal structures.
Dermoscopy is essentially free of complications because it is non-invasive. But there is minimal possibility of cross-infection between patients, especially with contact dermoscopy. We can use polarized non-contact dermatoscope and desinfect the lens of contact dermatoscope to avoid cross-infection between patients.
This article is written by dr. Caroline Astrid, supervised by dr. Stephen Akihiro Wirya, MS, RCPSC-UK (London), Sp.DV.
References:
Errichetti, E., G. Stinco. 2016. Dermoscopy in General Dermatology: A Practical Overview. Dermatol Ther (Heidelb) 6(4): 471–507. doi: 10.1007/s13555-016-0141-6.
Lallas, A., J. Giacomel, G. Argenziano, B. Garcia-Garcia, D. Gonzales-Fernandez, I. Zalaudek, F. Vazquez-Lopez. 2014. Dermatology in general dermatology: practical tips for the clinician.Br J Dermatol 170(3):514-26. doi: 10.1111/bjd.12685.
Russo, T., V. Piccolo, A. Lallas, G. Argenziano. 2016. Recent advances in dermoscopy. F1000Res. 2016; 5: F1000 Faculty Rev-184. doi: 10.12688/f1000research.7597.1.
Sonthalia, S., S. Yumeen, F. Kaliyadan. 2021. Dermoscopy Overview and Extradiagnostic Applications. Statpearls. https://www.ncbi.nlm.nih.gov/books/NBK537131/ accessed March 22nd, 2022.
Thomas, L., S. Dalle. 2007.Dermoscopy provides useful information for the management of melanonychia striata. Dermatologic Therapy, Vol. 20, 2007, 3–10.
Usatine, R.P., L.K. Shama, A.A. Marghoob, N. Jaimes. 2018. Dermoscopy in family medicine: A primer. J Fam Pract. 67(12):E1-E11.
Wu, X., M.A. Marchetti, A.A. Marghoob. 2015. Dermoscopy: not just for dermatologists. Melanoma Manag; 2(1): 63–73. doi: 10.2217/mmt.14.32.
https://dermnetnz.org/cme/dermoscopy- course/dermoscopy-of-benign-melanocytic-lesions