Melanoma Diagnoses Can Vary Widely Among Pathologists

Potential for both overdiagnosis and underdiagnosis, patient confusion

man using microscope

THURSDAY, June 29, 2017 (HealthDay News) -- Pathologists can vary widely when assessing skin biopsies for melanoma, particularly when the case is not clear-cut, according to a study published online June 28 in The BMJ.

Joann Elmore, M.D., M.P.H., professor at the University of Washington School of Medicine in Seattle, and colleagues collected 240 different skin biopsies ranging from an ordinary mole to advanced melanoma. The study authors sent off the glass slides, in groups of 36 or 48 slides, to 187 pathologists across the United States. The pathologists reviewed the same slides on two occasions, at least eight months apart. Elmore's team then compared the pathologists against themselves and a gold standard consensus diagnosis for each slide reached by a panel of pathology experts.

Pathologists often agreed on their diagnosis in cases at either extreme. But lesions that were not that straightforward produced a lot of disagreement, the investigators found. The pathologists agreed with the consensus diagnosis less than half of the time in these middle-ground cases, with agreement ranging from 25 to 43 percent. Agreement with themselves ranged from 35 to 63 percent. One slide in particular produced 18 different diagnoses from 36 pathologists, representing the full range from common mole up to invasive and heavily pigmented melanoma.

"Efforts to improve clinical practice should include using a standardized classification system, acknowledging uncertainty in pathology reports, and developing tools such as molecular markers to support pathologists' visual assessments," the authors conclude.

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