There were 928 patients with newly diagnosed NHL presenting to a participating NCCN site between July 1, 2000, and December 31, 2004, in the database. Of these, 731 patients were referred from other centers, had a documented pathologic diagnosis before presentation at the NCCN, had a final diagnosis of one of the 10 NHL subtypes, and were thus eligible for inclusion in this analysis.
Review of the abstracted data identified 66 patients for whom the referring and NCCN assessed diagnoses were discordant. Of these, diagnoses for 42 patients were deemed truly discordant after central and site investigator review. One additional pathologically discordant case was identified among the sample of concordant cases reviewed and is included among the discordant cases for this analysis. Overall, our pathologic discordance rate was 6% (95% CI, 4% to 8%; ).
Referral and Final Pathologic Diagnoses for Patients With Non-Hodgkin's Lymphoma (n = 731)
Pathologic concordance was highest for DLBCL, FL, and MZL. NCCN hematopathologists agreed with all 286 of the cases designated as DLBCL at the referring centers. However, 15 of the cases diagnosed as DLBCL at the NCCN center were assigned different diagnoses at the referring center, including FL (n = 6), Burkitt's lymphoma (n = 2), lymphoblastic lymphoma (n = 1), MCL (n = 1), MZL (n = 1), unspecified B-cell lymphoma (n = 1), and a diagnosis other than NHL (n = 3, Hodgkin's lymphoma, malignant thymoma, and anaplastic carcinoma). Of the 11 cases diagnosed as FL at the NCCN center, but assigned a different diagnosis at the referring center, eight cases had been classified using older classification schema or were called unspecified B-cell lymphomas; one was called SLL, one was called FL3, and one was called NMZ. The total number of cases diagnosed at the NCCN center as MZL, which included EMZ, NMZ, and SMZ, was small at 58 cases. Discordance occurred in only three cases; two were classified at the referral center as unspecified B-cell lymphoma, and one was classified as SLL. Seven cases of MCL had been assigned a different diagnosis at the referring center, including four cases called SLL. Conversely, three of 29 cases of SLL were discordant, two of which were initially called MCL.
The final diagnosis with the highest proportion of pathologic discordance (13%) was FL3, although the total number of cases was small (n = 32). Of the four discordant cases of FL3, two were called FL2, one was called FL1, and one was called FL NOS at the referring center.
lists the basis of the change in pathologic diagnosis at the NCCN center. In four (9%) of the 43 cases, the pathologic diagnosis at the referring center was preliminary, with further evaluation recommended. For all other cases, the referring center pathology was apparently final. Most commonly, no additional studies were performed at the NCCN center (44%), and the change in diagnosis reflected a different interpretation of the existing data. In 21%, one or more additional biopsies were performed, and in 26%, other studies were performed, primarily immunoperoxidase stains. Fluorescent in situ hybridization cytogenetics was performed in one case.
Basis of the Change in Pathologic Diagnosis at the NCCN Center
The potential effect on treatment of pathologic discordance is presented in . Treatment category discordance occurred in 5% of cases overall (95% CI, 3% to 7%) and in 35 (81%) of the 43 patients for whom pathology was discordant. Two percent of patients with DLBCL were assigned a pathologic diagnosis at the referral center for which less aggressive therapy might be given, thus missing the opportunity for cure. In addition, all of the patients with FL3 who were pathologically discordant were also discordant with respect to treatment category, with the original diagnosis falling into the indolent category in all cases.
Referral and Final Treatment Category for Patients With Non-Hodgkin's Lymphoma (n = 731)
FNA and core biopsies accounted for 9% (n = 68) and 19% (n = 142) of initial biopsies at referral sites, respectively. There was no statistically significant difference in concordance between those who had FNA (94%; n = 64) or core biopsies (93%; n = 132) and those who had other biopsy types (94%, n = 492; P = .76). The proportions of nodal and extra-nodal referrals were 61% (n = 473) and 34% (n = 258), respectively. There was no statistically significant difference in concordance between nodal (94%; n = 443) and extranodal referral specimens (95%; n = 245; P = .47). Overall, 60% of cases (n = 437) had ancillary testing before presentation at the NCCN, with 28% (n = 120), 61% (n = 266), and 12% (n = 51) having flow cytometry, immunohistochemistry, or both tests, respectively. There was no statistically significant difference in concordance between referral specimens with (95%; n = 415) and without ancillary testing (93%; n = 273; P = .24).