Journal of Pathology Informatics (Jan 2019)

Validation of whole-slide digitally imaged melanocytic lesions: Does z-stack scanning improve diagnostic accuracy?

  • Bart Sturm,
  • David Creytens,
  • Martin G Cook,
  • Jan Smits,
  • Marcory C. R. F. van Dijk,
  • Erik Eijken,
  • Eline Kurpershoek,
  • Heidi V. N Küsters-Vandevelde,
  • Ariadne H. A. G. Ooms,
  • Carla Wauters,
  • Willeke A. M. Blokx,
  • Jeroen A. W. M. van der Laak

DOI
https://doi.org/10.4103/jpi.jpi_46_18
Journal volume & issue
Vol. 10, no. 1
pp. 6 – 6

Abstract

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Background: Accurate diagnosis of melanocytic lesions is challenging, even for expert pathologists. Nowadays, whole-slide imaging (WSI) is used for routine clinical pathology diagnosis in several laboratories. One of the limitations of WSI, as it is most often used, is the lack of a multiplanar focusing option. In this study, we aim to establish the diagnostic accuracy of WSI for melanocytic lesions and investigate the potential accuracy increase of z-stack scanning. Z-stack enables pathologists to use a software focus adjustment, comparable to the fine-focus knob of a conventional light microscope. Materials and Methods: Melanocytic lesions (n = 102) were selected from our pathology archives: 35 nevi, 5 spitzoid tumors of unknown malignant potential, and 62 malignant melanomas, including 10 nevoid melanomas. All slides were scanned at a magnification comparable to use of a ×40 objective, in z-stack mode. A ground truth diagnosis was established on the glass slides by four academic dermatopathologists with a special interest in the diagnosis of melanoma. Six nonacademic surgical pathologists subspecialized in dermatopathology examined the cases by WSI. Results: An expert consensus diagnosis was achieved in 99 (97%) of cases. Concordance rates between surgical pathologists and the ground truth varied between 75% and 90%, excluding nevoid melanoma cases. Concordance rates of nevoid melanoma varied between 10% and 80%. Pathologists used the software focusing option in 7%–28% of cases, which in 1 case of nevoid melanoma resulted in correcting a misdiagnosis after finding a dermal mitosis. Conclusion: Diagnostic accuracy of melanocytic lesions based on glass slides and WSI is comparable with previous publications. A large variability in diagnostic accuracy of nevoid melanoma does exist. Our results show that z-stack scanning, in general, does not increase the diagnostic accuracy of melanocytic.

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