AUTHOR=Menke Joshua R. , Aypar Umut , Bangs Charles D. , Cook Stephen L. , Gupta Srishti , Hasserjian Robert P. , Kong Christina S. , Lin Oscar , Long Steven R. , Ly Amy , Menke Jacob A. S. , Natkunam Yasodha , Ruiz-Cordero Roberto , Spiteri Elizabeth , Ye Julia , Zadeh Sara L. , Gratzinger Dita A. 

TITLE=Performance of MYC, BCL2, and BCL6 break-apart FISH in small biopsies with large B-cell lymphoma: a retrospective Cytopathology Hematopathology Interinstitutional Consortium study

JOURNAL=Frontiers in Oncology

VOLUME=14

YEAR=2024

URL=https://www.frontiersin.org/journals/oncology/articles/10.3389/fonc.2024.1408238

DOI=10.3389/fonc.2024.1408238

ISSN=2234-943X

ABSTRACT=<sec><title>Introduction</title><p>Fluorescence <italic>in situ</italic> hybridization (FISH) is an essential ancillary study used to identify clinically aggressive subsets of large B-cell lymphomas that have <italic>MYC, BCL2</italic>, or <italic>BCL6</italic> rearrangements. Small-volume biopsies such as fine needle aspiration biopsy (FNAB) and core needle biopsy (CNB) are increasingly used to diagnose lymphoma and obtain material for ancillary studies such as FISH. However, the performance of FISH in small biopsies has not been thoroughly evaluated or compared to surgical biopsies.</p></sec><sec><title>Methods</title><p>We describe the results of <italic>MYC, BCL2,</italic> and <italic>BCL6</italic> FISH in a series of 222 biopsy specimens, including FNAB with cell blocks, CNBs, and surgical excisional or incisional biopsies from 208 unique patients aggregated from 6 academic medical centers. A subset of patients had FNAB followed by a surgical biopsy (either CNB or excisional biopsy) obtained from the same or contiguous anatomic site as part of the same clinical workup; FISH results were compared for these paired specimens.</p></sec><sec><title>Results</title><p>FISH had a low hybridization failure rate of around 1% across all specimen types. FISH identified concurrent <italic>MYC</italic> and <italic>BCL2</italic> rearrangements in 20 of 197 (10%) specimens and concurrent <italic>MYC</italic> and <italic>BCL6</italic> rearrangements in 3 of 182 (1.6%) specimens. The paired FNAB and surgical biopsy specimens did not show any discrepancies for <italic>MYC</italic> or <italic>BCL2</italic> FISH; of the 17 patients with 34 paired cytology and surgical specimens, only 2 of the 49 FISH probes compared (4% of all comparisons) showed any discrepancy and both were at the <italic>BCL6</italic> locus. One discrepancy was due to necrosis of the CNB specimen causing a false negative <italic>BCL6</italic> FISH result when compared to the FNAB cell block that demonstrated a <italic>BCL6</italic> rearrangement.</p></sec><sec><title>Discussion</title><p>FISH showed a similar hybridization failure rate in all biopsy types. Ultimately, <italic>MYC, BCL2</italic>, or <italic>BCL6</italic> FISH showed 96% concordance when compared across paired cytology and surgical specimens, suggesting FNAB with cell block is equivalent to other biopsy alternatives for evaluation of DLBCL or HGBCL FISH testing.</p></sec>