Validation of diagnostic accuracy with whole-slide imaging compared with glass slide review in dermatopathology

Background: Teledermatopathology has evolved from static images to whole slide imaging (WSI), which allows for remote viewing and manipulation of tissue sections. Previous studies of WSI in teledermatopathology predated College of American Pathologists (CAP) telepathology validation guidelines. Objective: We conducted a comprehensive retrospective WSI validation study of routine dermatopathology cases, adhering to CAP guidelines. Method: In all, 181 consecutive cases arranged into 3 categories (inflammatory, melanocytic, nonmelanocytic proliferations) were reviewed by 3 board-certified dermatopathologists via traditional microscopy (TM) and WSI. Intraobserver (TM vs WSI), TM intraobserver and interobserver (TM vs TM), and WSI interobserver (WSI vs WSI) concordance was interpreted using a 3-tier system. Results: TM versus WSI intraobserver concordance (86.9%; 95% confidence interval [CI] 83.7-89.6) did not differ from TM versus TM intraobserver concordance (90.3%; 95% CI 86.7-93.1) or interobserver concordance (WSI: 89.9%; 95% CI 87.0-92.2, and TM: 89.5%; 95% CI 86.5-91.9). Melanocytic proliferations had the lowest TM versus WSI intraobserver concordance (75.6%; 95% CI 68.5-81.5), whereas inflammatory lesions had the highest TM versus WSI intraobserver concordance (96.1%; 95% CI 91.8-98.3). Nonmelanocytic proliferations had an intraobserver concordance of 89.1% (95% CI 83.4-93.0). Limitations: Efficiency and other logistical WSI parameters were not evaluated. Conclusion: Intraobserver and interobserver diagnostic concordance between WSI and TM was equivalent. Therefore, WSI appears to be a reliable diagnostic modality for dermatopathology.