first cluster there were 15 cases characterized by 1p and/or 16p . CREBBP and STAT6 were the most frequently mutated genes (67%), followed by TNFRSF14 (62%). Clinically, there was a female predominance (12/15; 80%), and inguinal presentation (10/15; 67%) with a frequent diffuse growth pattern (6/15; 40%). The second cluster comprised 14 cases without 1p or 16p CNN-LOH but 5 cases showed 1p deletion. CREBBP was the most frequently mutated gene (77%) followed by STAT6 (57%), KMT2D (50%), TNFRSF14 (43%) and EZH2 (36%) mutations. Clinically, there was a female predominance (9/14; 64%), some inguinal presentation (6/13; 46%) but diffuse growth pattern was rare (3 cases). In the third cluster there were 15 cases characterized by low number of genetic alterations. CREBBP was not mutated and CNN-LOH was not identified.Clinically, no sex predilection and rare inguinal presentation was observed. The BCL6 translocated cases were equally distributed among the three groups.Conclusions: BCL2-negative FLs are genetically and clinically a heterogeneous disease. Three different genetic profiles were identified that correlated with some clinical features. Groups 1 and 2 had in common the frequent occurrence of STAT6 and CREBBP mutations; however, they differed in the extent of 1p and 16p CNN-LOH and deletions. Group 3 showed low mutational level and different clinical features. MAP2K1 mutations were not identified in any of the cases indicating that BCL2-negative FL and pediatric-type FL are two different entities. Introduction: Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) is an uncommon subtype of HL; the optimal management of stage I-II remains undefined. Methods: We conducted a multi-center retrospective study including patients (pts) ≥16 years (yr) with CD20+ stage I-II NLPHL diagnosed from 1995-2018. Management included observation after excision, single agent rituximab (R), chemotherapy (CT), radiation therapy (RT), and combined modality therapy (CMT=RT+systemic therapy). Primary outcomes were progression-free survival (PFS, by clinical, radiographic or pathologic progression) and overall survival (OS). Outcomes were measured with the Kaplan-Meier method with uni-and multivariable analyses (MVA) conducted with Cox regression. Results: We identified 437 pts with stage I-II NLPHL with median age 38 yr (range, 16-90) and median follow up of 5 yr (interquartile range=2.0-8.2). The majority were male (n=307 [70%]), had stage I (n=241 [55%]), ECOG 0-1 (n=366 [84%]), and were staged by PET-CT (n=295 [68%]). The 5-yr PFS and OS were 86.7% and 97.6%, respectively. 5-yr PFS by treatment were: 89.7% for RT (n=199 [46%], median dose 36 Gy), 92.5% for CMT (n=160 [37%]), 69.9% for CT ABSTRACT 145 (n=37 [8%]), 92.9% for observation (n=29 [7%]), and 33.3% for R (n=12 [3%]). CT only regimens were ABVD (n=27, 3 with R), R-CHOP (n=9), and R-COMP (n=1). CMT systemic therapies were ABVD (n=116, 19 with R), R-CHOP (n=24), R (n=15), MOPP (n=3), BEACOPPesc (n=1), and CVP (n=1). On univariable analysis, stage II (p=0.008), age (continuous...