[Classification of indolent B-cell lymphomas : Novelties and open questions].

The 5th edition of the WHO classification (WHO-HAEM5) and the International Consensus Classification (ICC) have considerable overlap but also some distinct differences in categorizing indolent B‑cell lymphomas. Most differences with the expected impact on the daily diagnostic routine relate to follicular lymphoma (FL). Grading of FL remains mandatory only in the ICC; a diffuse growth pattern in an FL with > 15 blasts per high-power field (FL grade 3A) is not automatically classified as DLBCL according to WHO-HAEM5, and an FL subtype with unusual morphology (blastoid or large centrocyte) and biology is recognized as an entity only in the WHO-HAEM5. With the exception of B‑prolymphocytic leukemia, which is no longer acknowledged in WHO-HAEM5, there are only minor differences between both classifications and include updated names of entities, improved diagnostic criteria, and upgrades from provisional to definite entities.