Three Key Practice Updates in Non-Hodgkin Lymphoma Classification for 2026

Original abstract

Lymphoid neoplasms present many challenges in routine surgical pathology practice, given the numerous forms of non-Hodgkin lymphoma that must be distinguished from each other through careful morphologic evaluation supplemented by an ever-growing battery of ancillary studies that may include immunohistochemistry, flow cytometry, in situ hybridization studies, and, increasingly, next generation sequencing. A further complicating factor is the existence of two partially-overlapping but distinct classification systems currently in widespread clinical practice, the 5th edition World Health Organization classification and the International Consensus Classification. This review provides practical updates in three important areas. First, we discuss the evaluation and classification of follicular lymphoma, one of the most common small B-cell neoplasms, and highlight how to distinguish conventional follicular lymphoma from other forms of follicular lymphoma with very different clinical features and management. Secondly, we describe the current approach to high grade B-cell lymphomas, including "double hit" lymphomas and high-grade B-cell lymphoma, not otherwise specified, and how these challenging cases should be distinguished from the much more common diffuse large B-cell lymphoma, not otherwise specified. Finally, we briefly describe the features of common nodal T-cell lymphomas, including the T-follicular helper cell lymphomas, anaplastic large cell lymphoma, and peripheral T-cell lymphoma, NOS. In each of these areas, we provide guidance on helpful ancillary studies and advice for navigating current classification systems.