Quality assessment in diagnostic molecular pathology: experience from a German-Austrian-Swiss multicenter trial

In order to assess the current technical standard of diagnostic molecular pathology, we have conducted a multicenter trial with 34 participating pathology laboratories in Germany, Austria and Switzerland. Formalin-fixed, paraffin-embedded tissue blocks were selected from 15 cases, comprising 4 B-cell non-Hodgkin's lymphomas, 4 T-cell non-Hodgkin lymphomas, 4 cases with lymphadenitis, 2 cases with confirmed tuberculosis and 1 case of sarcoidosis. All participating laboratories received one 10-microm section from each of the 15 cases to detect clonality using immunoglobulin heavy chain (IgH) gene or T-cell receptor (TCR)-gamma gene rearrangement analysis in 12 and mycobacterial DNA in 3 cases. In addition, participants had to answer technical questions about the application of internal quality controls and performance of fragment length or sequence analysis. Correct results were reported in 80% and 90% for IgH and TCR-gammagene rearrangement analysis, respectively, and in 83% for mycobacterial DNA analysis. No significant differences in the quality of results were obvious when the individual techniques used for molecular analysis were compared. However, when two independent techniques were used by the same laboratory, a higher rate of correct results was obtained for IgH and TCR rearrangement analysis. In conclusion, this study demonstrates a high technical standard of molecular diagnostic adjuncts among the participating laboratories. Regular multicenter trials with a greater number of participating laboratories working in this field will be indispensable to ensure a continuing or increasing standard in diagnostic molecular pathology.