A Case of Chemotherapy-Refractory “THRLBCL likeTransformation of NLPHL” SuccessfullyTreated with Lenalidomide

Nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) is a subtype of nonclassical Hodgkin lymphoma (HL). Itresemblesnon-Hodgkinlymphoma(NHL),byexpressingclassicBcellmarkerssuchasCD20andCD79ahoweverlacksdefinitiveHL markers (such as CD15 and CD30). Tcell histiocyte-rich large B cell lymphoma (THRLBCL), on the other hand, is a distinctentityclassifiedunderNHLandconsideredavariantofdiffuselargeBcelllymphoma(DLBCL).NLPHLcanlookmorphologicallyandimmunologicallysimilartoTHRLBCLandoftenposesadiagnosticchallenge.NeoplasticcellsinbothNLPHLandTHRLBCLexpress B cell markers and are typically scattered in a background of reactive cells. *e two major differences are the backgroundcell type and the morphologic pattern. Despite having a phenotypic resemblance, they have distinct biologic behavior and clinicalcourse. NLPHLtypically has anindolent course,andTHRLBCLhas anaggressivecourse. Hence,differentiatingthese twoentitiesis critical not only for prognosis but for treatment purposes. Of note, NLPHL has a small risk of transformation to an aggressivelymphoma such as THRLBCL.