Lymph node excisions provide more precise lymphoma diagnoses than core biopsies: a French Lymphopath network survey.

According to experts' guidelines, lymph node surgical excision (SE) is the standard of care for lymphoma diagnosis. However, core needle biopsy (CNB) has widely spread in the lymphoma diagnostic work-up over years. The aim of this study was i) to display the largest multicentric inventory of lymph nodes sampled either by CNB or SE in patients with suspected lymphoma and ii) to compare their diagnostic performance in routine pathological practice. We reviewed 32,285 cases registered in the French Lymphopath network that provides a systematic expert review of all lymphoma diagnoses in France, and evaluated the percentage of CNB and SE cases accurately diagnosed according to the WHO classification. Although CNB led to 92.3% complete diagnoses and appeared to be a reliable method of investigation for most patients with suspected lymphoma, it remained less conclusive than SE that yielded 98.1% of complete diagnoses. Discordance rates between referral and expert diagnoses were higher on CNB (23.1%) than SE (21.2%; P=0.004) and referral pathologists provided more cases with unclassified lymphoma or equivocal lesion through CNB. In such cases, expert review improved the diagnostic work-up by classifying ~90% of cases, with higher efficacy on SE (93.3%) than CNB (81.4%; P<10-6). Moreover, diagnostic concordance for reactive lesions was higher on SE than CNB (P=0.009). Overall, although CNB accurately diagnoses lymphoma in most instances, it increases the risk of erroneous or non-definitive conclusions. This large-scale survey also emphasizes the need for systematic expert review in cases of lymphoma suspicion, especially in those sampled by CNB.