Diagnostic Concordance of Pathological Methods and Reports of Hematopathologists Compared to Local Nonspecialized Pathologists in the Diagnosis of Lymphoma in Mexico

Background: Distinct diagnostic assays and algorithms are employed by contemporary pathologists when seeking to identify lymphoma. There is a paucity of data on the degree of concordance between pathologists diagnosing lymphoma and its subtypes in different institutional settings in Latin America. The objective of this study was to assess the concordance between lymphoma diagnoses made via tissue biopsy by local pathologists and after review of these specimens by more specialized hematopathologists. Methods: This prospective, noninterventional and multicenter study was conducted at seven sites in Mexico from January 2017 to October 2017. Eligible biopsy samples were from patients with a previous diagnosis of lymphoma on lymph node biopsy or a diagnosis of extranodal lymphoma, with adequate tissue preservation and adequate amount of tissue for the review analysis. Patients receiving either chemotherapy or corticosteroids before sampling of tissue biopsies were excluded. Seven sites representing local pathologists and three hematopathologists participated in the study. The same biopsy tissues reviewed by the local pathologists were also sent to the hematopathologists participating in this study. Physicians in charge of patients' treatment decided whether to make any changes to a patient's treatment decision when comparing diagnosis results from the local pathologists and hematopathologists. The concordance in diagnosis results were classified into 3 categories: diagnostic agreement (i.e. the local pathologist and hematopathologist diagnoses concurred), minor discrepancy (i.e. there was a difference in diagnosis but it didn't change the treatment decision) and major discrepancy (i.e. there was a difference in diagnosis and it changed the treatment decision based on guidelines from the National Comprehensive Cancer Network). Results: Of 111 samples received, 105 met eligibility criteria for full review by hematopathologists and were included for full analysis. The median (range) patient age was 53 (16-94) years. More specimens were obtained from women (n = 57; 54.3%). A total of 53 (50.5%) patients were recruited from private institutions and the remaining (52; 49.5%) from public institutions. Within the 105 biopsies, a total of 89 cases were diagnosed as lymphoma by hematopathologists, including non-hodgkin's lymphoma (NHL; n = 72; 68.6%) and hodgkin's lymphoma (HL; n = 17; 16.2%). The most common subtype of NHL diagnosed was diffuse large B cell lymphoma (DL