We conducted a retrospective review of discordant pathology for lymphoma patients treated at the Princess Margaret Hospital between 2000 and 2003. We identified 2818 lymphoma patients of which 1567 (38%) met inclusion criteria with 167 discordant cases (discordance rate 15.7%). Six reviewers blinded to clinical management rated potential for harm on a minimal to severe scoring. The majority (67.6%) received a rating of moderate to severe. Review of actual clinical management revealed unnecessary surgical procedures, incorrect chemotherapy and under or over treatment of patients. For discordant cases, 8.4% were identified as having severe actual harm. This means that 1/6 patients diagnosed with lymphoma may have a change in diagnosis after pathologic review, 1/9 will have discordance with the potential to cause moderate to severe consequences, and 1/75 will experience significant clinical harm. We conclude that pathologic discordance in lymphoma is common and can lead to patient harm.

We conducted a retrospective review of discordant pathology for lymphoma patients treated at the Princess Margaret Hospital between 2000 and 2003. We identified 2818 lymphoma patients of which 1567 (38%) met inclusion criteria with 167 discordant cases (discordance rate 15.7%). Six reviewers blinded to clinical management rated potential for harm on a minimal to severe scoring. The majority (67.6%) received a rating of moderate to severe. Review of actual clinical management revealed unnecessary surgical procedures, incorrect chemotherapy and under or over treatment of patients. For discordant cases, 8.4% were identified as having severe actual harm. This means that 1/6 patients diagnosed with lymphoma may have a change in diagnosis after pathologic review, 1/9 will have discordance with the potential to cause moderate to severe consequences, and 1/75 will experience significant clinical harm. We conclude that pathologic discordance in lymphoma is common and can lead to patient harm.