Purpose To prospectively assess the clinical impact of expert review of lymphoma diagnosis in France. Materials and Methods From January 2010 to December 2013, 42,145 samples from patients with newly diagnosed or suspected lymphomas were reviewed, according to the 2008 WHO classification, in real time by experts through the Lymphopath Network. Changes in diagnosis between referral and expert review were classified as major or minor according to their potential impact on patient care. Results The 42,145 reviewed samples comprised 36,920 newly diagnosed mature lymphomas, 321 precursor lymphoid neoplasms, 314 myeloid disorders, and 200 nonhematopoietic neoplasms, with 4,390 benign lesions. There were 4,352 cutaneous and 32,568 noncutaneous lymphomas. The most common mature noncutaneous lymphomas were diffuse large B-cell lymphomas (32.4%), follicular lymphomas (15.3%), classic Hodgkin lymphomas (13%), peripheral T-cell lymphomas (6.3%) of which angioimmunoblastic T-cell lymphomas (2.3%) were the most frequent, and mucosa-associated lymphoid tissue lymphomas (5.8%). A diagnostic change between referral and expert review occurred in 19.7% of patients, with an estimated impact on patient care for 17.4% of patients. This rate was significantly higher for patients sent with a provisional diagnosis seeking expert second opinion (37.8%) than for patients sent with a formal diagnosis (3.7%). The most frequent discrepancies were misclassifications in lymphoma subtype (41.3%), with 12.3% being misclassifications among small B-cell lymphoma entities. Fewer than 2% of changes were between benign and malignant lymphoid conditions. Minor changes (2.3%) mostly consisted of follicular lymphoma misgrading and diffuse large B-cell lymphoma subtype misclassification. Conclusion To our knowledge, this study provides the largest ever description of the distribution of lymphoma entities in a western country and highlights how expert review significantly contributes to a precise lymphoma diagnosis and optimal clinical management in a proportion of patients.

Reliable information regarding the current prevalence of peripheral T-cell lymphoma (PTCL) entities is missing. Herein we report on the frequency of PTCL entities in France between 2010 and 2013. Using Lymphopath, a national lymphoma network established by the French National Cancer Agency, which covers about 70 % of all lymphomas currently diagnosed in France, we found that PTCL comprised 6.5 % of non-cutaneous lymphomas with angioimmunoblastic T-cell lymphoma (AITL) being the most frequent (739 cases; 36 %), followed by peripheral Tcell lymphoma not otherwise specified (PTCL-NOS) (550 cases, 27%). These data were verified in an independent data set from a transnational research consortium active in three European countries. In comparison to epidemiologic data reported previously, we show that AITL is by far the most common PTCL subtype. In light of the results of recent molecular findings highlighting the heterogeneity of T-cell lymphomas and the advent of targeted therapies, these data have important implications for both basic and clinical research.Peripheral T-cell lymphomas (PTCLs) represent diverse and complex diseases, estimated to represent an overall 10-15% of all lymphomas worldwide, with the highest incidence rates occurring in Asia.1,2 The relative prevalence of PTCL entities delineated according to the criteria of the REAL (1994) /WHO (2001) classification systems, was evaluated in multiple institutions in the late 1990s and early 2000s, based on retrospective cohorts of patients. In those series, PTCL-NOS (a "by default" diagnosis for cases not fulfilling the criteria for other more specific entities) was the most frequent entity, followed by anaplastic large cell lymphoma (ALCL) and AITL, while extranodal entities, in general, accounted for a small proportion of the cases. 1,3,4 This worldwide epidemiology was most recently addressed by the International PTCL study, which reviewed more than 1,300 patients diagnosed with PTCL between 1990 and 2002 in North America, Europe and Asia.5 In this cohort, PTCL-NOS was the most common diagnosis (25,9%), followed by AITL (18,5%), representing 30.4% and 21.7% of non-cutaneous PTCL, respectively (Figure 1). 5This study also confirmed geographic variations in the distribution of PTCL entities, notably demonstrating that the highest frequencies of AITL and enteropathy-associated Tcell lymphoma (EATL) are in Europe.Here, we provide recent data obtained from a large prospective survey in France. The prevalent analysis of PTCL was derived from data collected through Lymphopath, a national network of 33 expert reference centers for hematopathology which was established by the French National Cancer Agency in 2010. Non-expert pathologists are encouraged to refer every newly diagnosed lymphoma for review to a Lymphopath center. Diagnoses provided by experts, following slide review and additional ancillary techniques performed in the reference center, are entered into a central database. Of the 31,401 non-cutaneous lymphomas reviewed in Lymphopath over four years (20...

These authors contributed equally to this work.