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 p athology, we have conducted a multicenter trial with 34 participating patho logy laboratories in Germany, Austria and Switzerland. Formalin-fixed, para ffin-embedded tissue blocks were selected from 15 cases, comprising 4 B-cel l non-Hodgkin's lymphomas, 4 T-cell non-Hodgkin lymphomas, 4 cases with lym phadenitis, 2 cases with confirmed tuberculosis and 1 case of sarcoidosis. All participating laboratories received one 10-mu m section from each of th e 15 cases to detect clonality using immunoglobulin heavy chain (IgN) gene or T-cell receptor (TCR)-gamma gene rearrangement analysis in 12 and mycoba cterial DNA in 3 cases. In addition, participants had to answer technical q uestions 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-gamma gene 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 obt ained for IgH and TCR rearrangement analysis. In conclusion, this study dem onstrates a high technical standard of molecular diagnostic adjuncts among the participating laboratories. Regular multicenter trials with a greater n umber of participating laboratories working in this field will be indispens able to ensure a continuing or increasing standard in diagnostic molecular pathology.