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NIHR Signal Dermoscopy plus visual inspection aids melanoma diagnosis

Published on 5 March 2019

doi: 10.3310/signal-000742

Dermoscopy, using a relatively cheap handheld magnifying device alongside naked eye observation, is more accurate in the diagnosis of melanoma than visual inspection alone. It can also provide a photographic record which can be used for reference during follow-up.

This NIHR-funded review included 104 studies of skin lesions in the dermatology clinic that looked suspicious or were present in those at high risk of developing melanoma. Melanoma is a rare form of skin cancer. Inspection of the lesions in-person using dermoscopy was also more accurate than looking at dermoscopic images remotely.

The findings provide stronger evidence to support current guidelines for the use of dermoscopy in the assessment of suspicious pigmented skin lesions in secondary care and support further training of non-specialists in the technique.

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Why was this study needed?

Melanoma was the fifth most common cancer in the UK in 2015, with 15,900 new cases each year. Over the last decade, incidence rates have increased by 50%.  

Without treatment, melanoma can spread to other parts of the body. Visual inspection is usually one of the first steps taken in the diagnosis of a suspicious looking skin lesion. However, magnification techniques such as dermoscopy are increasingly being used by GP’s and specialists to assess whether high-risk lesions, because of appearance or family history, could be cancerous. The method uses magnification and a strong light provided in a small handheld device to allow physicians to examine the fine patterns in the top layers of skin in more detail, through an oil interface.

This Cochrane review aimed to investigate the accuracy of dermoscopy compared to visual inspection and whether there was a difference if skin specialists used the device themselves compared with looking at clinical images that had been sent to them.

What did this study do?

This systematic review included 104 studies (42,788 skin lesions) that evaluated the use of dermoscopy in adults with suspicious skin lesions either in-person or remotely.

The studies included pigmented skin lesions, atypical moles, lesions suspicious of melanoma or lesions in those who were at high risk of developing melanoma based on information such as family history. Most studies were European, with three studies from the UK.  

Inclusion of a wide range of study types, selective recruitment of participants and inconsistency in the reporting of study conduct does impact the reliability of the results.

As the average prevalence of melanoma was 12% in the in-person studies and 25% in the remote studies, this suggests a specialist population such as those attending dermatology outpatients and with higher likelihood of melanoma than is seen by GPs.

 

 

What did it find?

  • Meta-analyses of data from 26 in-person studies comparing dermoscopy plus visual inspection to 13 in-person visual inspection studies suggested that using dermoscopy was over four times more accurate than visual inspection on its own.
  • Similar results were found when comparing 60 image-based dermoscopy studies to 11 image-based visual inspection studies. Dermoscopic images were five times more accurate.
  • Interpreting these results for a hypothetical group of 1,000 patients with a 12% chance of having a melanoma, suggests that 110 correct diagnoses (true positives) could be made in the dermoscopy group and 91 in the visual inspection only group - if a 20% unnecessary excisions (false positive) rate is accepted.
  • In the same group of 1,000 hypothetical patients, 44 unnecessary excisions (false positives) might occur in the dermoscopy group and 220 in the visual inspection group if a 20% missed diagnosis (false negative) rate is accepted.
  • Overall, accuracy was found to be higher for in-person diagnoses using dermoscopy compared with image-based dermoscopy evaluations.
  • The review also found that accuracy of interpretation was increased when the diagnosis of melanoma was made by individuals with more expertise and training.

What does current guidance say on this issue?

The NICE 2017 Clinical Knowledge Summary supports the use of dermoscopy for assessment of lesions in primary care, prior to referral for potential biopsy or removal of the lesion. The NICE 2015 guideline also recommends using dermoscopy in the assessment of all pigmented skin lesions that have been either referred for assessment or identified during follow-up in secondary or tertiary care.

The NICE guideline further advises the use of dermoscopy to take photographic images at first presentation of an atypical skin lesion. The images should then be used as a comparison when reviewing the clinical appearance of the lesion three months later to identify potential early signs of melanoma.

What are the implications?

The review mostly looked at the use of dermoscopy by dermatologists in secondary care where it is in standard use in the NHS. This review supports that practice.

However, GPs with specialist interests in dermatology are increasingly using dermoscopy, often sending images to secondary care for review. Few studies in this review looked at this application for triaging who needs to be seen in person.

However, depending on the level of training, this study suggests that accuracy is improved by in-person assessment.

Citation and Funding

Dinnes J, Deeks JJ, Chuchu N et al; Cochrane Skin Cancer Diagnostic Test Accuracy Group. Dermoscopy, with and without visual inspection, for diagnosing melanoma in adults. Cochrane Database Syst Rev. 2018;12:CD011902.

This project was funded by the National Institute for Health Research (NIHR) Cochrane Systematic Reviews Programme Grant (13/89/15).

Bibliography

Cancer Research UK. Melanoma skin cancer statistics. London: Cancer Research UK; 2015.

NHS website. Skin cancer (melanoma). London: Department of Health and Social Care; 2017.

NICE. Melanoma and pigmented lesions. Clinical Knowledge Summary. London: National Institute for Health and Care Excellence; 2017.

NICE. Melanoma: assessment and management. NG14, London: National Institute for Health and Care Excellence; 2015.

Why was this study needed?

Melanoma was the fifth most common cancer in the UK in 2015, with 15,900 new cases each year. Over the last decade, incidence rates have increased by 50%.  

Without treatment, melanoma can spread to other parts of the body. Visual inspection is usually one of the first steps taken in the diagnosis of a suspicious looking skin lesion. However, magnification techniques such as dermoscopy are increasingly being used by GP’s and specialists to assess whether high-risk lesions, because of appearance or family history, could be cancerous. The method uses magnification and a strong light provided in a small handheld device to allow physicians to examine the fine patterns in the top layers of skin in more detail, through an oil interface.

This Cochrane review aimed to investigate the accuracy of dermoscopy compared to visual inspection and whether there was a difference if skin specialists used the device themselves compared with looking at clinical images that had been sent to them.

What did this study do?

This systematic review included 104 studies (42,788 skin lesions) that evaluated the use of dermoscopy in adults with suspicious skin lesions either in-person or remotely.

The studies included pigmented skin lesions, atypical moles, lesions suspicious of melanoma or lesions in those who were at high risk of developing melanoma based on information such as family history. Most studies were European, with three studies from the UK.  

Inclusion of a wide range of study types, selective recruitment of participants and inconsistency in the reporting of study conduct does impact the reliability of the results.

As the average prevalence of melanoma was 12% in the in-person studies and 25% in the remote studies, this suggests a specialist population such as those attending dermatology outpatients and with higher likelihood of melanoma than is seen by GPs.

 

 

What did it find?

  • Meta-analyses of data from 26 in-person studies comparing dermoscopy plus visual inspection to 13 in-person visual inspection studies suggested that using dermoscopy was over four times more accurate than visual inspection on its own.
  • Similar results were found when comparing 60 image-based dermoscopy studies to 11 image-based visual inspection studies. Dermoscopic images were five times more accurate.
  • Interpreting these results for a hypothetical group of 1,000 patients with a 12% chance of having a melanoma, suggests that 110 correct diagnoses (true positives) could be made in the dermoscopy group and 91 in the visual inspection only group - if a 20% unnecessary excisions (false positive) rate is accepted.
  • In the same group of 1,000 hypothetical patients, 44 unnecessary excisions (false positives) might occur in the dermoscopy group and 220 in the visual inspection group if a 20% missed diagnosis (false negative) rate is accepted.
  • Overall, accuracy was found to be higher for in-person diagnoses using dermoscopy compared with image-based dermoscopy evaluations.
  • The review also found that accuracy of interpretation was increased when the diagnosis of melanoma was made by individuals with more expertise and training.

What does current guidance say on this issue?

The NICE 2017 Clinical Knowledge Summary supports the use of dermoscopy for assessment of lesions in primary care, prior to referral for potential biopsy or removal of the lesion. The NICE 2015 guideline also recommends using dermoscopy in the assessment of all pigmented skin lesions that have been either referred for assessment or identified during follow-up in secondary or tertiary care.

The NICE guideline further advises the use of dermoscopy to take photographic images at first presentation of an atypical skin lesion. The images should then be used as a comparison when reviewing the clinical appearance of the lesion three months later to identify potential early signs of melanoma.

What are the implications?

The review mostly looked at the use of dermoscopy by dermatologists in secondary care where it is in standard use in the NHS. This review supports that practice.

However, GPs with specialist interests in dermatology are increasingly using dermoscopy, often sending images to secondary care for review. Few studies in this review looked at this application for triaging who needs to be seen in person.

However, depending on the level of training, this study suggests that accuracy is improved by in-person assessment.

Citation and Funding

Dinnes J, Deeks JJ, Chuchu N et al; Cochrane Skin Cancer Diagnostic Test Accuracy Group. Dermoscopy, with and without visual inspection, for diagnosing melanoma in adults. Cochrane Database Syst Rev. 2018;12:CD011902.

This project was funded by the National Institute for Health Research (NIHR) Cochrane Systematic Reviews Programme Grant (13/89/15).

Bibliography

Cancer Research UK. Melanoma skin cancer statistics. London: Cancer Research UK; 2015.

NHS website. Skin cancer (melanoma). London: Department of Health and Social Care; 2017.

NICE. Melanoma and pigmented lesions. Clinical Knowledge Summary. London: National Institute for Health and Care Excellence; 2017.

NICE. Melanoma: assessment and management. NG14, London: National Institute for Health and Care Excellence; 2015.

Dermoscopy, with and without visual inspection, for diagnosing melanoma in adults

Published on 7 December 2018

Dinnes, J.,Deeks, J. J.,Chuchu, N.,Ferrante di Ruffano, L.,Matin, R. N.,Thomson, D. R.,Wong, K. Y.,Aldridge, R. B.,Abbott, R.,Fawzy, M.,Bayliss, S. E.,Grainge, M. J.,Takwoingi, Y.,Davenport, C.,Godfrey, K.,Walter, F. M.,Williams, H. C.

Cochrane Database Syst Rev Volume 12 , 2018

BACKGROUND: Melanoma has one of the fastest rising incidence rates of any cancer. It accounts for a small percentage of skin cancer cases but is responsible for the majority of skin cancer deaths. Although history-taking and visual inspection of a suspicious lesion by a clinician are usually the first in a series of 'tests' to diagnose skin cancer, dermoscopy has become an important tool to assist diagnosis by specialist clinicians and is increasingly used in primary care settings. Dermoscopy is a magnification technique using visible light that allows more detailed examination of the skin compared to examination by the naked eye alone. Establishing the additive value of dermoscopy over and above visual inspection alone across a range of observers and settings is critical to understanding its contribution for the diagnosis of melanoma and to future understanding of the potential role of the growing number of other high-resolution image analysis techniques. OBJECTIVES: To determine the diagnostic accuracy of dermoscopy alone, or when added to visual inspection of a skin lesion, for the detection of cutaneous invasive melanoma and atypical intraepidermal melanocytic variants in adults. We separated studies according to whether the diagnosis was recorded face-to-face (in-person), or based on remote (image-based), assessment. SEARCH METHODS: We undertook a comprehensive search of the following databases from inception up to August 2016: CENTRAL; MEDLINE; Embase; CINAHL; CPCI; Zetoc; Science Citation Index; US National Institutes of Health Ongoing Trials Register; NIHR Clinical Research Network Portfolio Database; and the World Health Organization International Clinical Trials Registry Platform. We studied reference lists and published systematic review articles. SELECTION CRITERIA: Studies of any design that evaluated dermoscopy in adults with lesions suspicious for melanoma, compared with a reference standard of either histological confirmation or clinical follow-up. Data on the accuracy of visual inspection, to allow comparisons of tests, was included only if reported in the included studies of dermoscopy. DATA COLLECTION AND ANALYSIS: Two review authors independently extracted all data using a standardised data extraction and quality assessment form (based on QUADAS-2). We contacted authors of included studies where information related to the target condition or diagnostic threshold were missing. We estimated accuracy using hierarchical summary receiver operating characteristic (SROC),methods. Analysis of studies allowing direct comparison between tests was undertaken. To facilitate interpretation of results, we computed values of sensitivity at the point on the SROC curve with 80% fixed specificity and values of specificity with 80% fixed sensitivity. We investigated the impact of in-person test interpretation; use of a purposely developed algorithm to assist diagnosis; observer expertise; and dermoscopy training. MAIN RESULTS: We included a total of 104 study publications reporting on 103 study cohorts with 42,788 lesions (including 5700 cases), providing 354 datasets for dermoscopy. The risk of bias was mainly low for the index test and reference standard domains and mainly high or unclear for participant selection and participant flow. Concerns regarding the applicability of study findings were largely scored as 'high' concern in three of four domains assessed. Selective participant recruitment, lack of reproducibility of diagnostic thresholds and lack of detail on observer expertise were particularly problematic.The accuracy of dermoscopy for the detection of invasive melanoma or atypical intraepidermal melanocytic variants was reported in 86 datasets; 26 for evaluations conducted in person (dermoscopy added to visual inspection), and 60 for image-based evaluations (diagnosis based on interpretation of dermoscopic images). Analyses of studies by prior testing revealed no obvious effect on accuracy; analyses were hampered by the lack of studies in primary care, lack of relevant information and the restricted inclusion of lesions selected for biopsy or excision. Accuracy was higher for in-person diagnosis compared to image-based evaluations (relative diagnostic odds ratio (RDOR) 4.6, 95% confidence interval (CI) 2.4 to 9.0; P < 0.001).We compared accuracy for (a), in-person evaluations of dermoscopy (26 evaluations; 23,169 lesions and 1664 melanomas),versus visual inspection alone (13 evaluations; 6740 lesions and 459 melanomas), and for (b), image-based evaluations of dermoscopy (60 evaluations; 13,475 lesions and 2851 melanomas),versus image-based visual inspection (11 evaluations; 1740 lesions and 305 melanomas). For both comparisons, meta-analysis found dermoscopy to be more accurate than visual inspection alone, with RDORs of (a), 4.7 (95% CI 3.0 to 7.5; P < 0.001), and (b), 5.6 (95% CI 3.7 to 8.5; P < 0.001). For a), the predicted difference in sensitivity at a fixed specificity of 80% was 16% (95% CI 8% to 23%; 92% for dermoscopy + visual inspection versus 76% for visual inspection), and predicted difference in specificity at a fixed sensitivity of 80% was 20% (95% CI 7% to 33%; 95% for dermoscopy + visual inspection versus 75% for visual inspection). For b) the predicted differences in sensitivity was 34% (95% CI 24% to 46%; 81% for dermoscopy versus 47% for visual inspection), at a fixed specificity of 80%, and predicted difference in specificity was 40% (95% CI 27% to 57%; 82% for dermoscopy versus 42% for visual inspection), at a fixed sensitivity of 80%.Using the median prevalence of disease in each set of studies ((a), 12% for in-person and (b), 24% for image-based), for a hypothetical population of 1000 lesions, an increase in sensitivity of (a), 16% (in-person), and (b), 34% (image-based), from using dermoscopy at a fixed specificity of 80% equates to a reduction in the number of melanomas missed of (a), 19 and (b), 81 with (a), 176 and (b), 152 false positive results. An increase in specificity of (a), 20% (in-person), and (b), 40% (image-based), at a fixed sensitivity of 80% equates to a reduction in the number of unnecessary excisions from using dermoscopy of (a), 176 and (b), 304 with (a), 24 and (b), 48 melanomas missed.The use of a named or published algorithm to assist dermoscopy interpretation (as opposed to no reported algorithm or reported use of pattern analysis), had no significant impact on accuracy either for in-person (RDOR 1.4, 95% CI 0.34 to 5.6; P = 0.17), or image-based (RDOR 1.4, 95% CI 0.60 to 3.3; P = 0.22), evaluations. This result was supported by subgroup analysis according to algorithm used. We observed higher accuracy for observers reported as having high experience and for those classed as 'expert consultants' in comparison to those considered to have less experience in dermoscopy, particularly for image-based evaluations. Evidence for the effect of dermoscopy training on test accuracy was very limited but suggested associated improvements in sensitivity. AUTHORS' CONCLUSIONS: Despite the observed limitations in the evidence base, dermoscopy is a valuable tool to support the visual inspection of a suspicious skin lesion for the detection of melanoma and atypical intraepidermal melanocytic variants, particularly in referred populations and in the hands of experienced users. Data to support its use in primary care are limited, however, it may assist in triaging suspicious lesions for urgent referral when employed by suitably trained clinicians. Formal algorithms may be of most use for dermoscopy training purposes and for less expert observers, however reliable data comparing approaches using dermoscopy in person are lacking.

Expert commentary

In this analysis, the bottom line is that when used in the clinic by dermatologists, per 1,000 lesions assessed, the number of missed melanomas is reduced using dermoscopy. One hundred and ten melanomas would be correctly identified compared with 91 on visual inspection alone. The number of unnecessary excisions would also be reduced. It was calculated that 220 incorrect melanoma excisions would be made versus 44 lesions in the dermoscopy group.

This means dermatologists should be using dermoscopy to assess pigmented lesions and is in line with NICE guidance. The report makes some comments about algorithms (most useful for training practitioners) and use in primary care (little evidence) which suggests some evidence gaps.

Dr Michael Ardern-Jones, Associate Professor and Consultant Dermatologist, University of Southampton

The commentator declares no conflicting interests

Expert commentary

This review looks at a large number of studies of dermoscopy. The authors demonstrate a consistent and significant pattern, indicating that use of dermoscopy increases the likelihood of diagnosing melanoma more accurately, with reduction in unnecessary surgery.

Dermoscopy is now practiced widely by dermatologists, and this detailed, thorough review strongly supports the continued use of dermoscopy in the diagnosis of melanoma.

Moreover, many who presently use dermoscopy are not yet experts and should be encouraged to deepen their skills. Non-dermatologists should be encouraged to take on dermoscopy, and medical schools should consider teaching dermoscopy as part of core curriculum.

Professor Colin Fleming, Consultant Dermatologist, Honorary Professor of Dermatology, Ninewells Hospital and Medical School

The commentator declares no conflicting interests