Value of external quality assessment of the technical aspects of histopathology.

An external quality assessment scheme (EQAS) in the technical aspects of histopathology is described, and the results obtained over a two-year period assessed. The scheme involved 42 laboratories of varied work load, and the slides returned by the laboratories, both haematoxylin and eosin and special stains were marked by panels of four assessors. The reliability of assessment was checked by comparing the results of two separate panels of assessors, and by asking the same panel to assess the same set of slides on a different occasion. The participants' evaluation of the scheme was tested by questionnaire. The results show that the scheme described was considered to be of value by the great majority of the participants. The assessment of the slides by a panel was shown to be both reliable and reproducible. We believe that a general application of schemes such as the one described will maintain and improve standards in histopathology laboratories.