Systematic use of fluorescence in‐situ hybridisation and clinicopathological features in the screening of PDGFRB rearrangements of patients with myeloid/lymphoid neoplasms

Abstract

Conclusions: These findings suggest that a higher yield for the identification of PDGFRB rearrangement may result from an index of suspicion in patients with eosinophilia, monocytosis, bone marrow features of a myeloid neoplasm, and 5q31-33 rearrangement, and patients with Philadelphia-like B-ALL.

A Cryptic BCR-PDGFRB Fusion Resulting in a Chronic Myeloid Neoplasm With Monocytosis and Eosinophilia: A Novel Finding With Treatment Implications

“…Although limited by its observational nature, this case does highlight a potential pitfall in the diagnosis of myeloid neoplasms with eosinophilia, and supports the algorithmic approach recommended by Fang et al 17 in their recent publication describing the systematic use of PDGFRB FISH in such neoplasms.…”

“…10 This case also highlights the utility of a stepwise approach in using PDGRB FISH for accurate diagnosis of myeloid neoplasms with eosinophilia that do not have evidence of 5q31-33 alterations on routine karotypic analysis, in which the presence of eosinophilia cannot be attributed to other molecular or cytogenetic alterations, such as BCR-ABL1 translocation or alterations of PDGFRA. 17 Currently FISH is considered to be more practical and readily available in most commercial and academic settings. Although more advanced technologies such as RNA-seq are useful in identifying unknown gene partners in these neoplasms, as shown in our case, they are not readily accessible outside of the research setting, and therefore we do not currently recommend their routine use in the workup of such cases.…”

Chronic Myelomonocytic Leukemia: Hematopathology Perspective

“…Among these, PDGFRB rearrangements are most likely to present with monocytosis, [22] and although typically identifiable on routine karyotyping studies (located on 5q32), rare cryptic cases, only identifiable by FISH (fluorescence in situ hybridization) exist. [23,24] PDGFRA fusions are almost nearly always cryptic and only identifiable by FISH, demonstrating CHIC2 deletion. [1] In contrast, PDGFRB and JAK2 rearrangements are typically identifiable on routine karyotype studies.…”

Myeloid/Lymphoid Neoplasms with Eosinophilia and TK Fusion Genes, Version 3.2021, NCCN Clinical Practice Guidelines in Oncology

“…Conventional cytogenetic analysis for t(5;12) followed by confirmatory FISH testing with break-apart probes to assess the involvement of PDGFRB is the most effective approach to identify the fusion gene. 49 Confirmation of PDGFRB rearrangement by FISH is indicated in all patients with a 5q31;33 breakpoint.…”