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Dermoscopy lets dermatologists see skin cancers, scabies, hair loss in new light

Nearly 300 years after Johan Kolhaus used a skin surface microscope to examine the vessels of the nail bed, the term “dermatoskopie” made its first appearance in the scientific literature in the early 1920s, when German dermatologist Johann Saphier published a series of articles exploring the possible applications of a new device with a built-in light source. Pioneering research, conducted primarily by dermatologists in Europe and the United States, culminated in the Consensus Net Meeting on Dermoscopy in 2000, followed a year later by the First World Congress of Dermoscopy and the commercial launch of the first polarized dermatoscope.

In the 21st century, technological advances have led to earlier detection of melanoma and non-melanoma skin cancers, reduction of unnecessary excisions, and the discovery of applications for dermoscopy beyond the evaluation of pigmented lesions. Investigators have compiled a substantial and growing body of literature documenting the dermoscopic features of a broad range of skin disorders. For some conditions, dermoscopy reveals morphologic features that were previously unknown. “In psoriasis, for example, where we may use X100 or X200 magnification, we see vascular abnormalities and patterns that you cannot see with the naked eye,” said Giuseppe Micali, MD, professor and chair of the department of dermatology at the University of Catania, Italy. “Dermoscopy is absolutely revealing a new world made of new findings that we didn’t know before the use of this technology.”

Exploring alternative applications

Because most of the literature on dermoscopy focuses on the evaluation of pigmented lesions, Dr. Micali’s mission is to educate practicing clinicians about the many common conditions in which it has proven valuable as a tool for diagnosis and/or monitoring treatment. In addition to editing a textbook on the topic, Dr. Micali co-authored a review article in the Journal of the American Academy of Dermatology (2011;64:1135-46) discussing the dermoscopic features of 28 disorders. Robert A. Schwartz, MD, professor and head of dermatology at New Jersey Medical School, is a co-author of the JAAD article and a skin cancer expert. “Dermoscopy can really help with diseases of hair, with nail diseases, with psoriasis, with benign neoplasms such as clear cell acanthoma, port wine stains, with inflammatory diseases such as lichen planus, urticaria and urticaria vasculitis, rosacea, pigmented purpuris dermatosis, you name it,” Dr. Schwartz said. “It gives us a whole new perspective on these different morphologies.”[pagebreak]

Scabies is one disorder for which dermoscopy can transform clinical practice, Dr. Micali said. The JAAD review article cites studies confirming the effectiveness of dermoscopy in diagnosing scabies, including one showing that the diagnostic accuracy of video dermoscopy is equal to that of scraping. “In our department, we haven’t used scraping for more than five years,” Dr. Micali said. “Dermoscopy is much better, easier, and less time-consuming.” At magnifications of X100 to X600, video dermoscopy is preferable to hand-held dermoscopy for scabies, he added, as video dermoscopy makes the oval translucent body of the mite clearly visible. Dermoscopy also plays a key role in monitoring the treatment of scabies. “In the majority of cases, the patient comes back because they’re still itching, and we don’t know whether the itching is related to failure of treatment or because of irritation from the topical medication,” Dr. Micali said. “Parents don’t want their kids to go through scraping, but dermoscopy will give us the answer in three minutes. So it’s very, very important for patient compliance.” He noted that, “In Italy, dermoscopy for uses other than pigmented lesions is not reimbursed,” but said his hospital charges a reasonable fee of 50 euros, or about $70 at current exchange rates.

Dermoscopy is also proving useful in the diagnosis of several hair conditions, including androgenetic alopecia, alopecia areata, scarring alopecia, trichostasis spinulosa, trichotillomania, and a host of disorders of the hair shaft. “Dermoscopy is extremely helpful in the very early diagnosis of androgenetic alopecia, at the point where the patient can feel that something is different about his hair but the change is not clinically apparent,” Dr. Micali said. “It can detect hair shaft diameter and lead us to discover the miniaturization and the overall hair diameter diversity that is a hallmark of the disorder.” Dr. Schwartz pointed out that early intervention in male pattern baldness is thought to lead to more effective therapy, and that dermatologists can use dermoscopy to monitor treatment with minoxidil or finasteride. “Patients are very impressed, because they see changes to the hair through the dermoscopic images and are motivated to continue the treatment,” Dr. Micali added. He said that in androgenetic alopecia dermoscopy is performed on the hair of the frontal and parietal regions. A hair diameter diversity of greater than 20 percent is highly specific of the disease.

Although the use of dermoscopy to diagnose psoriasis is still developing, investigators using the higher magnifications of video dermoscopy have identified dilated, elongated, and convoluted capillaries in a distinctive “bushy” pattern that is peculiar to psoriasis. “This is important because some forms of psoriasis are very limited, and the physician can’t make a diagnosis without a biopsy and patch test if contact dermatitis is suspected,” Dr. Micali said. “If you use dermoscopy and you find this vascular pattern, then the diagnosis is simple. We tested this with a group of patients who had a single patch on the hand. In those patients who did not show this bushy pattern, histology confirmed a diagnosis of spongy dermatitis. All patients with the bushy pattern were found to have psoriasis.” For psoriasis patients on biologic therapy, dermoscopy can help to rule out a return of the disease, Dr. Micali said. “Sometimes they might also have nonspecific skin inflammation, or eczema, and think it’s psoriasis. Dermoscopy can tell us if it is or is not.”[pagebreak]

Detecting melanoma and non-melanoma skin cancer

Dermoscopy initially gained recognition as an effective method for the early recognition of malignant melanoma during the 1990s. According to a clinical review article published in JAAD (2005;52:109-21) dermoscopy “increases diagnostic accuracy between 5 percent and 30 percent over clinical visual inspection, depending on the type of skin lesion and experience of the physician.”

Technological advances in the past five years have yielded improvements in convenience and clinical utility, noted Ashfaq A. Marghoob, MD, the editor of the Atlas of Dermoscopy, a guide to the early recognition of melanoma. “The discovery that polarized light can be used to see dermoscopic structures without the need to touch or wet the skin was particularly important,” said Dr. Marghoob, an associate clinical professor of dermatology at Memorial Sloan-Kettering Cancer Center and the State University of New York at Stony Brook. “There’s certainly a convenience factor, but what we found was that there are structures you can see under polarized light that you can’t see under non-polarized light, and vice versa. The two modes are complementary, and there may be features only distinguishable with one type that are critical for the diagnosis of a particular lesion. So most experts now are leaning toward the use of hybrid scopes that allow you to toggle between polarized and non-polarized light when evaluating a lesion.”

Dermoscopy has clearly improved the sensitivity of the diagnosis of melanoma, Dr. Marghoob said. “It has especially improved our ability to detect the hypomelanotic and amelanotic melanomas, because there are dermoscopic criteria for non-pigmented lesions. These lesions would be visible to the naked eye but would not meet the ABCD criteria; they may be smaller than 6mm, for example. Dermoscopy would help you diagnose them.” Similarly, dermoscopy has improved the early diagnosis of non-melanoma skin cancers. “It has given us the ability to detect basal cell carcinomas and squamous cell carcinomas even when they’re as tiny as 1mm,” Dr. Marghoob said. “The advantage, obviously, is that whatever scar you’re going to end up with will be smaller.”

Sequential digital dermoscopy, the short-term monitoring of nevi for which a diagnosis is unclear, can also lead to the very early detection of melanomas. “Sometimes we see melanomas in which there are no criteria to make a diagnosis, so we take a dermoscopic image and then take another three months later. If any change occurs, it gets removed,” Dr. Marghoob said. “We’ve gotten to the point where we’re diagnosing clinically featureless melanomas. They’re also featureless on dermoscopy, but based on the change seen dermoscopically, they’re being diagnosed.”[pagebreak]

Improving the benign to malignant ratio of biopsied pigmented lesions and reducing the number of unnecessary excisions through dermoscopy is a key benefit to patients, said the experts. But leaving a lesion in place requires recognition of the dermoscopic features of benign lesions, as well as melanomas. Kelly Nelson, MD, director of the melanocytic lesions clinic and assistant professor of dermatology at Duke University Medical Center, sought to address an issue that was affecting her pediatric patients. “I had several patients with very large scars on their scalp because their doctors had noted moles and excised them. In some young patients it was almost deforming; they looked as though they had been in a car accident,” she said. “There was little information about typical nevi in children, so we decided to conduct a study to establish the clinical and dermoscopic patterns of typical scalp nevi in patients younger than 18.”

Dr. Nelson and her colleagues obtained clinical and dermoscopic images of 88 nevi in 39 children referred to either the pediatric dermatology clinic or the pigmented lesion clinic for other reasons. Based on the reassuring dermoscopic patterns observed, none of the nevi were excised. The study, which discusses in detail the clinical and dermoscopic features of the nevi, will be published in an upcoming issue of the British Journal of Dermatology. “I think there’s a huge potential in increasing the body of knowledge as it applies to dermoscopy in children, because they do have moles and their parents are concerned, particularly if a mole is larger than a pencil eraser,” Dr. Nelson said. “It can be pretty traumatic for a child to undergo an excision, so if you can avoid one by using dermoscopy to thoroughly understand the mole, then it’s a real value-add to the patient’s care.”[pagebreak]

Utilization lagging, but future looks bright

Despite a wealth of literature supporting the clinical utility of dermoscopy, its rate of adoption among clinicians outside the academic community appears to lag far behind that of Europe and Australia. A study published in the Australasian Journal of Dermatology (2011; 52:14-18) found that 98 percent of the 99 dermatologists who completed a survey reported using dermoscopy. The results of a survey mailed to U.S. fellows of the AAD, published in JAAD (2010; 63:412-19), indicated that 48 percent use dermoscopy. Dermoscopy users tended to be younger than 50, female, involved in resident training, and trained in the use of dermoscopy. The primary reasons given for not using dermoscopy included lack of training, lack of interest, the time required for dermoscopic examination, and a belief that dermoscopy would not affect clinical decision-making. The survey had a response rate of 38 percent. (See sidebar for more data on dermoscopy use.)

Dermoscopy use in the academic setting contrasts sharply with that of the AAD fellows who responded to the survey. Dr. Marghoob and his colleagues surveyed the directors and chief residents of all dermatology residency programs in the U.S. in 2000 and 2009 to assess their use of dermoscopy and total body photography, receiving a 75 percent response for the more recent survey. Dr. Marghoob reported that dermoscopy use in residency programs went from 51 percent to 84 percent, the number of residents receiving training increased from 38 percent to 90 percent, and the number of residents using dermoscopy went from 64 percent to 88 percent. “Although we don’t have a good idea of what’s happening on the community front, our gut feeling is that very few are using it,” Dr. Marghoob said. “But based on what’s occurring in residency, we know that as the older physicians retire and this newer generation is filling the void, it’s just going to become the norm as it is in Europe and Australia.”

Dr. Marghoob attributed the higher adoption rates in Europe and Australia to reimbursement for dermoscopy in several European countries and Australia’s designation of the training and utilization of dermoscopy as a “grade A recommendation” in its clinical practice guidelines for the management of melanoma. “There are no guidelines in the U.S. regarding dermoscopy and the AAD takes no stance on it, so its use is not promoted in that way,” said Dr. Marghoob. (The AAD does offer an educational product, Dermoscopy: A Guide for the Physician, to help members learn to use the technique in practice.) “However, in both the AAD and the American Academy of Family Physicians, more and more lectures on dermoscopy are given each year at the annual meeting. There is some market research that shows about one in four dermatoscopes sold in the U.S. are being sold to a non-dermatologist. Some may be nurse practitioners, but a good portion are probably general practitioners and family physicians.”

Response to her dermoscopy presentations at dermatology conferences points to a growing interest in its use, Dr. Nelson said. “Among community-based dermatologists, more people are asking questions about what type of dermatoscope they should get and how they should they capture the images of lesions they excise to help them learn. And then there are always a few who are very vocal about the fact that they don’t need dermoscopy.”[pagebreak]

Both Dr. Marghoob and Dr. Nelson emphasized that beyond their initial training, dermatologists will experience a learning curve over the course of a few years as they become proficient in utilizing dermoscopy. “Especially if they’re out of residency, any learning is a barrier,” said Dr. Marghoob. “You need to take at least one intense course, and then it takes between one and three years to become comfortable with interpretation.” Dr. Nelson noted that the benign to malignant ratio of excisions can actually increase at the outset. “Studies have shown that when practitioners have started incorporating dermoscopy into their practice, they end up removing more benign lesions, but after that initial ramp-up — when you’re trying to develop your own internal data set of what’s benign and what’s malignant — the number of benign excisions they perform goes down. So over time, the net effect is that they become more efficient in their biopsy practices and save patients from unnecessary excisions.”


Smartphone does dermoscopy

Thanks to dramatic improvements in smartphone cameras, several products are already on the market that allow dermatologists to attach a dermatoscope to a smart phone and perform mobile skin examinations. “The dermatoscope attachment clips onto the smart phone over the camera; so now you can see the image on a smart phone screen instead of having to peer through that little dermatoscope,” said Peter Lio, MD, a Chicago dermatologist and assistant professor of clinical dermatology and pediatrics at Northwestern University Feinberg School of Medicine. “You can enter patient information, and note where you’re taking the picture, and instantly send that information, along with the high-resolution digital image, to the patient’s chart. It’s also a great tool for teaching.”

What dermatoscope to choose?

Dermatologists considering adding dermoscopy to their diagnostic repertoire may wonder what dermatoscope to choose. According to Kelly Nelson, MD, director of the melanocytic lesions clinic and assistant professor of dermatology at Duke University Medical Center, “Any dermatoscope with adequate lighting is better than no dermatoscope. For those who want to tip toe’ into the field, one of the entry-level models that can be purchased for around $300 is a great way to get started. Just keep it in your lab coat pocket and start looking at what you’re seeing clinically.” Dermatologists who become more comfortable with the technology, she said, “may be ready to spend more for one of the more advanced dermatoscopes, such as the contact non-polarized with a brighter LED light, or a dermatoscope that can toggle between polarized and non-polarized and attach to a camera for dermoscopic photographs.”

Dermoscopy data

In their 2010 JAAD study, “Dermatoscopy use by US dermatologists: A cross-sectional survey,” authors Holly C. Engasser, MD, and Erin M. Warshaw, MD, gathered data on the use of dermoscopy from 3,228 respondents the largest U.S. survey to date regarding the technique. They found that 48 percent of respondents used dermoscopy. Other results from the survey are illustrated below.


 

Related Resources

Smartphone does dermoscopy
What dermatoscope to choose?
Dermoscopy data