13yrs male with ISOLATED neck lateral lymphadenopathy for ~2 months without any signs of disease/B symptoms.  
Biopsy of the lateral neck node (macro photo).  
 
SONOSCOPY: 22,8x18,4x9,5mm node: hypoechoic, with definite capsule. There is no definite hillus vissible, general vascularisation not prominent.  
Visual picture of specific lymphadenopathy.  
 
HISTO: Some large GCs with tumor population (oval), some "infiltrated" with disrupted FDC network (elongated) and interstitial interfollicular spread (as EBV IM) and diffuse zones with disrupted FDC networks with highly proliferating CB like "blastoid" cells in starry sky back (BL like picture/GCB IH, except MYC(-) and Bcl2/Mum1+ het. Normal reactive FCs at periphery (with weak CD10 and Bcl2(-)).  
 
IH: CD19+; CD22+ (weak); CD20/CD79a+ (heterog); Bcl6/CD10/LMO2+; Bcl2/CD43(-/+); Ig kappa+; cMYC(-); TdT(-); EBER/HHV8(-); MUM1+/-(focal); IgM+; CD30/CD138/IgD(-); Ki67 index 90%.  
 
 
FISH:  
MYC (8q24) break: NO.  
IRF4/DUSP22(6p25.3) translocation: NO.  
MYC/IGH t(8;14)(q24;q32) translocation: NO.  
Bcl2 break: NO.  
11q aberations: NO.  
 
MOLECULAR:  
CONVENTIONAL PCR: Not clonal IGH, IGK ir IGL and TCRB, TCRG ir TCRD locuses.  
NGS:  
Case was referred for molecular IG clonality assessment.  
DNA was extracted using Maxwell-16 FFPE Tissue LEV DNA Purification Kitl and subjected for IGH clonality assessment using BIOMED-2 protocol and PCR fragment analysis on ABI 3500 sequence analyzer. Both IGH FR1 (Tube A) and FR2 (Tube B) reactions detected clonal peak in the background yet with inconsistent sizing – in the different sides of the expected range interval. Therefore, additional Next generation sequencing analysis of the IGH FR2 region was performed (Invivoscribe kit, MiSeq instrument).  
Data were analyzed with Arrest/Interrogate, Vidjil and IMGT V-Quest tools.  
NGS data analysis revealed unproductive IGHV3-33*03 / IGHD5-12*01 / IGHJ4*02 rearrangement with <90% sequence identity to the IGHV3-33*03 suggesting considerable modification of germline sequence by AID and hypermutation. This may also explain inconsistent BIOMED-2 clonality assessment results .  
NGS sequencing data was confirmed with Sanger sequencing.  
 
 
PROPOSAL: Pediatric DLBCL (GCB type)(non clonal; without known FISH abberations) NOS (with folliculothropism).  
 
Thank You.