Study raises concern over accuracy of melanoma diagnoses

June 28, 2017, British Medical Journal
Melanoma in skin biopsy with H&E stain — this case may represent superficial spreading melanoma. Credit: Wikipedia/CC BY-SA 3.0

Concerns over the accuracy of melanoma diagnoses are raised in a study of US pathologists published by The BMJ today.

The results show that diagnoses can vary among pathologists, particularly for cases in the middle of the disease spectrum, suggesting the potential for both overdiagnosis and underdiagnosis.

Melanoma is a type of skin cancer that develops from skin cells called melanocytes. Diagnosis relies on visual assessment of skin samples (biopsies) under a microscope by a pathologist, but the reliability of the criteria used to diagnose these skin have never been established with rigorous standards.

Previous studies have suggested high levels of diagnostic disagreement among pathologists when interpreting , but results are conflicting.

So a team of researchers, led by Professor Joann Elmore at the University of Washington School of Medicine in Seattle, set out to measure the accuracy and reproducibility of pathologists' diagnoses of melanocytic skin lesions.

The study was inspired by Dr Elmore's experience as a patient undergoing a , which resulted in three different independent interpretations, ranging from benign to invasive . Ten years later she is healthy and doing research on the topic.

A total of 187 practicing pathologists from 10 US states were randomised to independently interpret the same set of skin biopsy cases on two separate occasions (phases 1 and 2), at least eight months apart.

Each case had been independently reviewed by a panel of three experienced skin pathologists and a consensus reference diagnosis reached.

Participants' interpretations were assigned to one of five classes: I, e.g. mild atypia; II, e.g. moderate atypia; III, e.g. severe atypia or melanoma in situ; IV, e.g. early invasive melanoma; and V, e.g. invasive melanoma.

Accuracy was measured by comparing the pathologists' interpretations with the panel's consensus reference diagnosis.

The highest levels of accuracy were found for class I mild lesions (92%) and class V high stage invasive melanoma (72%) - these cases are at the polar ends of the disease spectrum.

In contrast, interpretations for cases in the middle of the spectrum had noticeably lower accuracy, as less than half of the diagnoses were in concordance with the reference diagnosis; class II moderately atypical lesions (25%); class III severely atypical lesions and melanoma in situ (40%); and class IV early stage invasive melanoma (43%).

Pathologists' interpretations of the same case on two occasions also lacked reproducibility for cases in the middle of the spectrum.

At a population level, the researchers estimate that 83% of melanocytic biopsy diagnoses would have their diagnosis verified if reviewed by a consensus reference panel of experienced pathologists, with 8% of cases overinterpreted by the initial pathologist and 9% under-interpreted.

The authors outline some study limitations which could have introduced bias, but strengths included a large sample size and use of three reference standards to estimate accuracy.

They also point out that, in clinical practice, pathologists may have the opportunity to review more slides, obtain second opinions from colleagues, or request additional tests before making a diagnosis.

These results show that diagnoses ranging from moderately atypical lesions to early stage invasive melanoma are neither accurate nor reproducible, say the authors.

Efforts to improve clinical practice should include use of a standardized classification format, acknowledging uncertainty of specific diagnoses in pathology reports, and development of more sophisticated diagnostic tools to support , they conclude.

Explore further: Pathologists often disagree on breast biopsy results when diagnosing DCIS

More information: Pathologists' diagnosis of invasive melanoma and melanocytic proliferations: observer accuracy and reproducibility study, www.bmj.com/content/357/bmj.j2813

Opinion: When diagnostic uncertainty hits home blogs.bmj.com/bmj/2017/06/28/j … ncertainty-hits-home

Related Stories

Pathologists often disagree on breast biopsy results when diagnosing DCIS

March 21, 2016
A study applying B-Path (Breast Pathology) Study results to patient populations found that pathologists disagree with one another about 8 percent of the time when diagnosing a single breast biopsy slide. Discordance was more ...

Study examines diagnostic accuracy of pathologists interpreting breast biopsies

March 17, 2015
In a study in which pathologists provided diagnostic interpretation of breast biopsy slides, overall agreement between the individual pathologists' interpretations and that of an expert consensus panel was 75 percent, with ...

Pathologists vary in suggested therapy for melanocytic lesions

December 20, 2016
(HealthDay)—Pathologists have wide variability in treatment suggestions for melanocytic lesions, according to a study published in the January issue of the Journal of the American Academy of Dermatology.

Doctors say women with aytpia or DCIS should seek second opinions after breast biopsies

March 18, 2015
While doctors almost always agree on a pathological diagnosis of invasive breast cancer, there is room for improvement when diagnosing atypia (or atypical ductal hyperplasia-ADH) and DCIS (ductal carcinoma in-situ), Anna ...

Review of appendix cancer cases finds over diagnosis

June 8, 2017
Lesions of the appendix are being over diagnosed as invasive cancer, report University of California San Diego School of Medicine researchers in a paper published June 7 in the journal PLOS ONE.

Pathologists tend to reclassify prior nonmalignant diagnoses

August 17, 2012
(HealthDay) -- For dermatopathologists there is a trend toward reclassification of prior nonmalignant diagnoses of severely atypical dysplastic nevi as malignant, according to a study published in the September issue of the ...

Recommended for you

Breast cancer researcher warns against online genetic tests

June 18, 2018
We have never been so fascinated by the secrets inside our cells.

Genomics offers new treatment options for infants with range of soft tissue tumors

June 18, 2018
The genetic causes of a group of related infant cancers have been discovered by scientists at the Wellcome Sanger Institute, the University of Wuerzburg and their collaborators. Whole genome sequencing of tumours revealed ...

Non-coding DNA reveals a route by which advanced prostate cancer resists treatment

June 15, 2018
Two research teams converge on epigenetic switches that feed treatment-resistant metastatic prostate tumors. This research highlights the value of exploring gene regulation and large-scale structural changes in the cancer ...

Researchers peer inside cells to spy on cancer's on-off switch

June 15, 2018
Forty years after researchers first discovered it in fruit flies, a once-obscure cluster of proteins called PRC2 has become a key target for new cancer-fighting drugs, due to its tendency—when mutated—to bind to and silence ...

PIM-2 protein kinase regulates T-cell activity differently than PIM-1 or PIM-3 isoform

June 15, 2018
The PIM-2 protein kinase negatively regulates T cell responses in transplantation and tumor immunity, while PIM-1 and PIM-3 are positive regulators, report Medical University of South Carolina (MUSC) investigators in an article ...

Gene testing could identify men with prostate cancer who may benefit from immunotherapy

June 14, 2018
Scientists have identified a pattern of genetic changes that could pick out men with advanced prostate cancer who are likely to benefit from immunotherapy.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.