Validating whole-slide imaging for consultation diagnoses in surgical pathology

The interpretation of scanned whole-slide images (WSI) offers some theoretical advantages for long-distance, consultative diagnosis in surgical pathology. Few WSI validation studies have focused on difficult consultation cases.

To test intraobserver variability of WSI interpretations in cases that had been submitted for consultation using the same hardware and software configuration selected by a client.

The 217 cases (approximately 20 nearly consecutive cases received in consultation for each of 11 subspecialty groups) were scanned, uploaded to an image-distribution application, and interpreted by 26 pathologists who had reviewed the microscope slides an average of 47 days earlier. Independent pathologists identified and classified discrepancies between microscope slide and WSI diagnoses.

There were 2 major discrepancies (0.92%) and 8 minor discrepancies (3.7%). One major discrepancy reflected atypical versus nonatypical endometrial hyperplasia; the other related to reactive squamous changes versus carcinoma. Strengths of the study include the large sample size, the many pathologists involved, the degree of difficulty of the cases, and the duplication of scanning and software configuration projected to be used by a client. Although the average 43-day washout exceeds the 2-week interval recommended by an expert panel of the College of American Pathologists, an important limitation in this study was that pathologists commonly remember consultation cases for a long time.

Our results help support the safety and efficacy of WSI for surgical pathology diagnoses.