Expert second-opinion pathology review of lymphoma in the era of the World Health Organization classification.

BACKGROUND The World Health Organization (WHO) classification of hematologic malignancies, published in 2000, was designed to improve diagnostic accuracy by incorporating the latest in scientific understanding. The impact of the WHO classification on the frequency of diagnostic discrepancy in lymphoma is unknown. METHODS We reviewed all second-opinion pathology of lymphoma at our National Cancer Institute-designated Comprehensive Cancer Center (NCI-CCC) from January to June 2001 and from January to June 2006. Discrepancies between submitted and second-opinion diagnoses were scored based upon an a priori grading schema. RESULTS Major diagnostic revision was rendered in 65 of 365 cases (17.8%) in 2001 and 58 of 354 (16.4%) in 2006 (P=NS). Including cases reviewed and revised beforehand at another NCI-CCC, rates of major diagnostic revision were 21.4% and 18.6%, respectively (P=NS). Discrepancy rates varied by diagnosis, from Hodgkin lymphoma (10%) to Burkitt's lymphoma (75%). No association was seen for age, gender, race/ethnicity, biopsy type, or nature of referring center. CONCLUSIONS Clinically meaningful diagnostic revision occurs frequently with expert pathology review for a diagnosis of lymphoma. Despite the WHO classification, rates of diagnostic revision at our institution in 2001 and 2006 did not differ significantly. Given the potential harm from misdiagnosis, expert hematopathology review should be considered the standard of care.