Reactive lymphoid hyperplasia with giant follicles associated with post-therapeutic state of hematological malignancies: A report of six cases

Abstract

Aims and background. To further clarify the clinicopathological, molecular genetic and karyotypic findings of reactive lymph node hyperplasia with giant follicles (RL HGF ) associated with a posttherapeutic state of hematological malignancies, we studied eight such cases. Methods . Using formalin -fixed , paraffin -embedded sections, histological, immuno histochemical, in situ hybridization(ISH) ,andpolymerasechainreaction(PCR)were performed. Results . Six patients had a history of malignant lymphoma (diffuse large B-cell lym phoma [DLBCL] = 4 , marginal zone B-cell lymphoma = 2), and two had acute myeloid leukemia(AML).Sixpatientsinitiallypresentedwithlymphadenopathyoftheheadand neck area and the remaining one presented with swelling of the tonsil. All seven cases demonstrating analyzable metaphases showed a normal karyotype. Histologically, all eight lesions were characterized by numerous enlarged, bizarre-shaped coalescing lymphoidfollicleswithfollicularlysis.Immunohistochemicalandflow cytometrystudy demonstratedthe reactivenatureoftheB cellsinalleightlesions. However,threeofour eight cases demonstrated immunoglobulin heavy -chain (IgH) gene rearrangement on PCRstudy.Differentclonalband sweredetectedin theinitiallymphomatoustissueand RLHGF in one of the studied cases. There was no development of B-cell lymphoma or recurrence of B-cell lymphoma in any of the three lesions demonstrating IgH re arrangement. There w ere no human herpes virus type-8 + or human immunodeficien cy virus type-1 + cells in any of the eight lesion s. ISH demonstrated Epstein-Barr virus (EBV)-encodedsmallRNA(EBER)+cellsinonlytwolesions. PCRanalysesdemonstrat edthattherewasno Toxoplasma gondii DNAinanyoftheeightlesion s. Conclusions .AssuggestedinRLHGFposttransplant,RLHGFarisingaftertherapyfor hematological malignancies is also a consequence of chronic stimulation in the set tingofimmunederegulationratherthanvariousinfectiousagents.Itisimportantfor pathologists and clinicians to be aware of this type of lesion in diagnostic practice. Free full text available at www.tumorionline.it