Study raises concern over accuracy of melanoma diagnoses

June 28, 2017
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

Encouraging oxygen's assault on iron may offer new way to kill lung cancer cells

November 22, 2017
Blocking the action of a key protein frees oxygen to damage iron-dependent proteins in lung and breast cancer cells, slowing their growth and making them easier to kill. This is the implication of a study led by researchers ...

One-size treatment for blood cancer probably doesn't fit all, researchers say

November 22, 2017
Though African-American men are three times more likely to be diagnosed with a blood cancer called multiple myeloma, most scientific research on the disease has been based on people of European descent, according to a study ...

One in four U.S. seniors with cancer has had it before

November 22, 2017
(HealthDay)—For a quarter of American seniors, a cancer diagnosis signals the return of an old foe, new research shows.

Combination immunotherapy targets cancer resistance

November 22, 2017
Cancer immunotherapy drugs have had notable but limited success because in many cases, tumors develop resistance to treatment. But researchers at Yale and Stanford have identified an experimental antibody that overcomes this ...

Researchers discover specific tumor environment that triggers cells to metastasize

November 21, 2017
A team of bioengineers and bioinformaticians at the University of California San Diego have discovered how the environment surrounding a tumor can trigger metastatic behavior in cancer cells. Specifically, when tumor cells ...

New study points the way to therapy for rare cancer that targets the young

November 21, 2017
After years of rigorous research, a team of scientists has identified the genetic engine that drives a rare form of liver cancer. The findings offer prime targets for drugs to treat the usually lethal disease, fibrolamellar ...

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.