PMC8727142_01
Tumor histology and V-J frequency graphs. On the left are H&E sections from the DLBCL in the lymph node and CLL/SLL in the bone marrow. Inset: high-power view of the DLBCL in the lymph node. On the right are the V-J frequency graphs from FR3-J primers showing the clonal and LQ reads. The Y-axis is the % of total reads, and X-axis is the specific V-J rearrangement. Clonal reads are present in both the lymph node and bone marrow. C: clonal, V1-2*02/D5-12*01/J4*02, LQ: LymphoQuant control, and V1-69*01/D6-13*01/J6*03.
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fig1
Excisional biopsy of the enlarged node demonstrated diffuse large B-cell lymphoma (Figure 1, LN, Supplementary File 2). In contrast to the lymph node, there was no morphologic evidence of involvement by DLBCL in the bone marrow (Figure 1, BM). A representative FR3-J analysis with clonal reads is shown in Figure 1.
Alignment of the clonal sequence from lymph node and bone marrow. An identical clonal VDJ rearrangement is present in both specimens. The HCDR3 sequence is shown in red. The contribution of the V, D, and J segments to the HCDR3 sequence is shown (nucleotide, protein).
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fig2
Excisional biopsy of the enlarged node demonstrated diffuse large B-cell lymphoma (Figure 1, LN, Supplementary File 2). Alignment analysis showed that the clonal rearrangement contained an identical sequence in both specimens, indicating that the same clone of B cells was present in both locations (Figure 2). The same V1-2* 02/D5-12* 01/J4* 02 rearrangement was present in both lymph node and bone marrow specimens (Figure 2) confirming that the DLBCL in the lymph node arose as a result of Richter's transformation of a subclinical CLL/SLL.
Alignment of the clonal VDJ sequence to germline V1-2*02 The clonal sequence (FR1-J) from the lymph node and bone marrow shows an unmutated V region when aligned to the germline V gene. GL: germline sequence, LN: lymph node, and BM: bone marrow.
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fig3
Alignment to the germline IGHV1-2* 02 sequence showed that the V region remained in an unmutated state suggesting an origin from a naive B cell that had not yet experienced the germinal center reaction (Figure 3).
MRD after R-CHOP therapy. Clonal reads were detected at a low level in total DNA from bone marrow (BM) and peripheral blood (PB) and after R-CHOP therapy. The B-cell repertoire shows severe contraction in the peripheral blood after R-CHOP therapy. C: clonal and LQ: LymphoQuant.
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fig4
 Figure 4 shows the VJ frequency graphs for the FR1-J reactions after R-CHOP therapy. 
MRD after allogeneic transplant. Clonal reads were still present at day 30 after allotransplant in total DNA and CD19+ DNA but were extremely few in number to be visualized on the Y-axis. Clonal reads were not detected in total DNA and CD19+ B-cell DNA in peripheral blood (PB) at day 60 after transplant. The B-cell repertoire in the peripheral blood shows successful expansion and diversity at days 30 and 60 after transplant. C: clonal and LQ: LymphoQuant.
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fig5
However, at day 60 after transplant, the clonal sequence was not detected in either total or CD19+ B-cell DNA indicating successful eradication of the tumor clone (Figure 5).