Nordic immunohistochemical quality control.

The use of immunohistochemistry by pathologists has been steadily, almost logarithmically increasing during the last decade. There is no scientific indication that this trend will reverse or slow down. At the same time, quality control issues have not followed this tempo. In particular, external quality control has been neglected. In 1999, nine Scandinavian laboratories established organization, Nordic Quality Control (NordiQC), to provide external quality control in immunohistochemistry for Denmark, Norway, Sweden, and Finland. This commentary briefly describes the work of this organization.