The World Health Organization (WHO) lymphoma classification has been widely adopted by hematopathologists. However, its practical application by general pathologists is largely unknown. Using a hematopathology consultation program in Taiwan, we reviewed 406 cases. Diagnostic discrepancies were scored based upon whether the divergence would alter disease management according to National Comprehensive Cancer Network guidelines. Major discrepancies accounted for 55% (222/406), minor discrepancies for 5% (20/406) and agreement for 40% (164/406) cases. The more common groups in major discrepancies were non-diagnostic/ambiguous referral reports (116/222, 52%), tumor type revisions (52/222, 23%) and changes from malignant to benign lesions (32/222, 14%). In a total of 259 cases of lymphoma, the concordance rates were 41% (77/187) and 33% (24/72) for B-cell and T/natural killer (NK)-cell lymphomas, respectively. It appears that the WHO approach has made lymphoma classification rather poorly reproducible at least in countries where extensive use of an ancillary technique is not employed by general pathologists.
