Abstract
To compare the diagnostic accuracy of internet-based virtual microscopy with conventional light microscopy, in the context of renal biopsies assessed by participants in the UK National Renal Pathology External Quality Assessment (EQA) Scheme. 'Virtual slides' of current EQA cases were made available over the internet to participants in the scheme. The approach permitted what may reasonably be described as a randomized controlled trial of the diagnostic accuracy of this mode of telepathology, in the context of renal pathology. No significant difference in diagnostic accuracy could be detected between the diagnoses proffered on the basis of virtual slides and conventional slides; but using virtual slides took pathologists considerably longer. This result provides some encouragement for the implementation of such virtual slide-based telepathology systems. However, in failing to detect a difference, equivalence of diagnostic accuracy has not been proved; nor has the relevance of this result to other fields of histopathology been demonstrated. A decision to implement a diagnostic telepathology system requires consideration of numerous factors beyond diagnostic accuracy, including financial, legal, professional and ethical issues.