BEYOND THE NODES: HIDDEN LYMPHOID STRONGHOLDS — A CASE SERIES OF PRIMARY EXTRANODAL LYMPHOMAS

Abstract

Background: Extranodal lymphomas represent a diagnostically challenging and clinically diverse group of lymphoid neoplasms that arise outside the conventional lymph node chain. Primary extranodal sites — including the central nervous system (CNS), testis, breast, and omentum — are rarely affected, and their accurate recognition requires integration of clinical, radiological, histomorphological, and immunohistochemical data. Methods: We report a retrospective case series of four patients diagnosed with primary extranodal lymphoma at SRM Medical College Hospital and Research Centre, Chengalpattu, India (2024–2025). Specimens were processed by standard formalin-fixed paraffin-embedded technique; histopathological examination and immunohistochemistry (IHC) were performed in all cases. Results: The series includes: (1) a 60-year-old male with primary testicular diffuse large B-cell lymphoma (DLBCL); (2) a 58-year-old male with primary CNS lymphoma of B-cell origin with high Ki-67 proliferative index; (3) a 56-year-old female with primary breast non-Hodgkin lymphoma (NHL) of B-cell type; and (4) a 45-year-old female with follicular lymphoma (FL) presenting incidentally as a primary omental mass. In all cases, IHC confirmed B-cell lineage (CD20 positive, CD3-negative). The omental FL was further classified as grade 1, stage II, with positivity for CD10, BCL2, and BCL6 and a low Ki-67 of 8–10%. Conclusion: This case series highlights the morphological spectrum and diagnostic challenges of primary extranodal lymphomas across rare sites. Comprehensive histopathological and immunohistochemical evaluation is indispensable for accurate subtyping, prognostication, and treatment planning.