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Original Investigation
December 2017

Diagnostic Accuracy of Virtual Pathology vs Traditional Microscopy in a Large Dermatopathology Study

Author Affiliations
  • 1Dermatopathology Laboratory of Central States, Dayton, Ohio
  • 2Department of Dermatology, Boonshoft School of Medicine, Wright State University, Dayton, Ohio
  • 3Dermatology Residency Program, OhioHealth, Columbus, Ohio
  • 4Division of Dermatology, The Ohio State University, Columbus
  • 5Medical Specialties Department, Michigan State University College of Osteopathic Medicine, East Lansing
  • 6Statistical Consulting Center, College of Science and Mathematics, Wright State University, Dayton, Ohio
JAMA Dermatol. 2017;153(12):1285-1291. doi:10.1001/jamadermatol.2017.3284
Key Points

Question  Is diagnosis from whole-slide images (WSI) noninferior to diagnosis from glass slides for cutaneous specimens?

Findings  This large retrospective study of 499 representative dermatopathology cases found 94% intraobserver concordance between WSI and traditional microscopy (TM). Diagnosis from WSI was found statistically noninferior to diagnosis from glass slides compared with ground truth consensus diagnosis.

Meaning  In most cases, we found diagnosis from WSI noninferior to TM. The WSI method approached, but did not achieve, noninferiority for the subset of melanocytic lesions. Discordance in TM diagnosis of this challenging group is broadly recognized and further investigation of melanocytic neoplasms is recommended.


Importance  Digital pathology represents a transformative technology that impacts dermatologists and dermatopathologists from residency to academic and private practice. Two concerns are accuracy of interpretation from whole-slide images (WSI) and effect on workflow. Studies of considerably large series involving single-organ systems are lacking.

Objective  To evaluate whether diagnosis from WSI on a digital microscope is inferior to diagnosis of glass slides from traditional microscopy (TM) in a large cohort of dermatopathology cases with attention on image resolution, specifically eosinophils in inflammatory cases and mitotic figures in melanomas, and to measure the workflow efficiency of WSI compared with TM.

Design, Setting, and Participants  Three dermatopathologists established interobserver ground truth consensus (GTC) diagnosis for 499 previously diagnosed cases proportionally representing the spectrum of diagnoses seen in the laboratory. Cases were distributed to 3 different dermatopathologists who diagnosed by WSI and TM with a minimum 30-day washout between methodologies. Intraobserver WSI/TM diagnoses were compared, followed by interobserver comparison with GTC. Concordance, major discrepancies, and minor discrepancies were calculated and analyzed by paired noninferiority testing. We also measured pathologists’ read rates to evaluate workflow efficiency between WSI and TM. This retrospective study was caried out in an independent, national, university-affiliated dermatopathology laboratory.

Main Outcomes and Measures  Intraobserver concordance of diagnoses between WSI and TM methods and interobserver variance from GTC, following College of American Pathology guidelines.

Results  Mean intraobserver concordance between WSI and TM was 94%. Mean interobserver concordance was 94% for WSI and GTC and 94% for TM and GTC. Mean interobserver concordance between WSI, TM, and GTC was 91%. Diagnoses from WSI were noninferior to those from TM. Whole-slide image read rates were commensurate with WSI experience, achieving parity with TM by the most experienced user.

Conclusions and Relevance  Diagnosis from WSI was found equivalent to diagnosis from glass slides using TM in this statistically powerful study of 499 dermatopathology cases. This study supports the viability of WSI for primary diagnosis in the clinical setting.