Dermoscopy (a.k.a. dermatoscopy or epiluminescence microscopy) is the examination of cutaneous lesions, such as nevi, BCC (Basal Cell Carcinoma), SCC (Squamous Cell Carcinoma), melanoma etc., using a dermatoscope. Next to diagnosing pigmented and non-pigmented skin lesions, dermoscopy is also applied to diagnose hair and scalp diseases (trichoscopy), nail abnormalities, inflammatory entities (inflammoscopy) and skin infections and infestations (entomodermoscopy).
Dermoscopy is a non-invasive technique used by dermatologists and general practitioners to examine skin lesions, structures and patterns. It enables dermatologists to identify skin lesion types more accurately, hence reducing the need for costly and invasive procedures, such as biopsies and incisions. For patients, this reduces the chance of scarring and other discomfort.
Dermoscopy has definitely proven its value over the years. Especially in the case of skin cancer, it has proven to increase the detection of malignant melanoma as it increases visibility of melanoma-specific features.
A digital dermatoscope
An analog dermatoscope
The dermatoscope consists of a magnifying lens and a light source for increased visibility of subsurface skin structures. There are various types of dermatoscopes:
Digital vs analog dermatoscopes
Analog dermoscopy is also called Epiluminescence Microscopy (ELM). When using an analog dermatoscope, dermatologists will look into the magnifying lens for detailed observation of skin lesions. An analog dermatoscope can be combined with a digital camera or smartphone for clinical imaging purposes and follow-up of lesions over time.
In Digital Epiluminescence Microscopy (DELM) or videodermoscopy, on the other hand, dermatologists will use a digital dermatoscope, which comes with an integrated camera. It means the dermatologist will look at the digital camera screen for observation of lesions rather than through the magnifying lens.
Digital dermatoscopes allow dermatologists to take dermoscopic images of skin lesions during the patient examination. Some digital dermatoscopes also allow dermatologists to take close-up and/or clinical overview images without the need for an external camera.
Smartphone-connected dermatoscopes are on the rise. These devices consist of a smartphone combined with special add-on lenses and illumination to enable minute observation of skin lesions. High-end smartphones can generate pixel-perfect images. However, in medical imaging, extremely high imaging standards need to be met as well as other prerequisites in terms of medical compliance, hygiene and safety.
Polarized vs non-polarized dermatoscopes
With a non-polarized dermatoscope, dermatologists will need a contact liquid, such as a gel or oil, to cancel out skin surface reflections when putting the lens in contact with the skin. This means the device needs to be cleaned and disinfected after each use, which makes it less convenient. However, some superficial skin structures can only be perceived with a non-polarized dermatoscope.
Polarized devices use polarized light with or without a contact fluid, which allows for more accurate visualization of subsurface structures located at the superficial dermis or dermal-epidermal junction. Polarized dermatoscopes can typically be used in both contact and non-contact mode. Polarized light can be multispectral or white. This is an important difference because with multispectral light, dermatologists can visualize the distinct chromophores in the superficial skin layer which make up the skin color (melanin, hemoglobin etc.) . Spectral imaging can as such allow extraction of additional information the human eye fails to capture. This technique is based on the distinctive optical absorption properties of these pigments in the skin composition. Red light, for example, penetrates deeper into the skin whereas blue light is a better fit for viewing superficial structures.
Hybrid devices combine the best of both worlds. They allow to easily switch between polarized and non-polarized light, they can be used in both non-contact and contact mode with or without immersion fluids. Some dermatoscopes even come with special non-contact cones or spacers for optimal hygiene. Non-contact cones are also useful for the imaging of elevated skin lesions.
Some dermatoscopes are bundled with software to automate some of the processes in skin imaging and analytics. For example, images can be stored automatically for easy follow-up and reporting and even dermoscopic features can be identified automatically.
The rise of artificial, also called augmented, intelligence in medical imaging opens even more windows of opportunity. Augmented dermatology can automate recognition of complex skin patterns and features via deep learning algorithms. This can help to identify the early signs of malignancy, resulting in faster treatment for high-risk patients.
Dermoscopy, also known as epiluminescence microscopy or dermatoscopy, is vital in the timely diagnosis of skin lesions, and more specifically skin cancer. Dermatologists should use a hybrid, digital and all-in-one dermatoscope to closely examine skin lesions and, at the same time, improve workflow. Augmented dermoscopy can further increase accuracy and efficiency by automating and enhancing the detection of malignant lesions and, more specifically, melanoma.