College of American Pathologists

  News Release


Published on May 1, 2013

Contact: Julie Monzo
Phone: 800-323-4040, ext. 7538

Ensuring the Future of Digital Pathology

College of American Pathologists Offers First Evidence-Based Guideline for Validating Whole Slide Imaging

Northfield, IL—The College of American Pathologists (CAP) released today a new evidence-based guideline, “Validating Whole Slide Imaging for Diagnostic Purposes in Pathology.” The guideline is the first of its kind and is now available in the CAP’s peer-reviewed journal, Archives of Pathology & Laboratory Medicine.

The document serves as a practical guide for pathologists and laboratories seeking to confirm the accuracy and concordance of their own whole slide imaging (WSI) systems for diagnostic work, while ensuring the digital tool is being properly used for its intended clinical purpose in an effort to deliver optimal patient care.

“We developed the guideline in anticipation of wider adoption of WSI in clinical practice,” said Liron Pantanowitz, MD, FCAP, the lead author of the guideline and associate professor in the Departments of Pathology and Biomedical Informatics at the University of Pittsburgh. “The guideline marks a significant step forward in demonstrating the value of this emerging technology for diagnostic use.”

Dr. Pantanowitz, editor-in-chief of the Journal of Pathology Informatics and president of the Association for Pathology Informatics, led a panel of North American experts in digital pathology to develop the guideline. Based on collective experiences and an extensive global literature review, the expert panel concluded that validation of WSI is crucial to ensure that diagnostic performance based on digitized slides is at least equivalent to that of glass slides and light microscopy.

Among the key points of the 12 recommendations outlined in the guideline are:

  • Validation of the entire WSI system, involving pathologists trained to use the system, should be performed in a manner which emulates the laboratory’s actual clinical environment.
  • It is recommended that such a validation study include at least 60 routine cases per application, assessing intraobserver diagnostic concordance between digitized and glass slides viewed at least two weeks apart.
  • It is important that the validation process confirms that all material present on a glass slide to be scanned is included in the digital image.

Currently, the US Food and Drug Administration does not approve WSI systems for primary diagnosis. However, pathologists practicing abroad can implement the guideline immediately in concordance with their country’'s regulatory guidelines for using WSI in making primary diagnoses.

“The pathology community has been awaiting the development of guidelines by organizations such as CAP concerning the implementation of WSI for diagnostic work,” said Andrew J. Evans, MD, PhD, FRCPC, staff pathologist and associate professor at the University Health Network, Laboratory Medicine Program at Toronto General Hospital in Canada and member of the expert panel. “Following the completion of our own validation study at UHN, we have begun using WSI to render primary diagnoses. Since many other centers in Canada are preparing to implement WSI for clinical use, there is a substantial appetite north of the border for the final version of this paper.”

WSI technology has several advantages for pathologists, including portability; ease of sharing and retrieval of archival images; and ability to make use of computer-aided diagnostic tools. Pathologists today are using WSI in teaching, research, and for handling consults from small, rural hospitals with no on-site pathologist. As the use of WSI expands, pathologists are seeing quicker turnaround times with the same quality of care.

The CAP Pathology & Laboratory Quality Center (the Center), a forum for developing evidence-based guidelines and consensus recommendations, provided the process for creating the guideline. The guideline will be updated as appropriate as new evidence-based research becomes available.

The CAP offers tools and resources to help further understanding and implementation of the guideline, including a summary of the recommendations. More information about how others are using digital pathology can be found in the CAP’s ebook, New Paths...New Choices: Pathology in an Era of Advancing Science and Disruptive Health Economics, specifically chapter 7, “Digital Pathology: New Technology Breaks the Distance Barrier.”

The CAP also will host a webcast on Friday, May 17 to provide an overview of the guideline. Registration information will be available on in the near future.

About the College of American Pathologists

As the leading organization for board-certified pathologists, the College of American Pathologists (CAP) serves patients, pathologists, and the public by fostering and advocating excellence in the practice of pathology and laboratory medicine worldwide. With more than 18,000 physician members, the CAP has led as the gold standard in laboratory accreditation for 50 years. Find more information about the CAP at