Evaluation of EWSR1/FUS rearrangements by FISH and NKX2.2 immunoexpression in simple bone cysts of the jaw

Adepitan A Owosho; Shokoufeh Shahrabi-Farahani; Katherine A DeColibus; Alivia M Shasteen; Kurt F Summersgill

doi:10.1016/j.oooo.2023.07.050

Evaluation of EWSR1/FUS rearrangements by FISH and NKX2.2 immunoexpression in simple bone cysts of the jaw

Oral Surg Oral Med Oral Pathol Oral Radiol. 2023 Aug 1:S2212-4403(23)00595-3. doi: 10.1016/j.oooo.2023.07.050. Online ahead of print.

Authors

Adepitan A Owosho¹, Shokoufeh Shahrabi-Farahani², Katherine A DeColibus², Alivia M Shasteen³, Kurt F Summersgill³

Affiliations

¹ Department of Diagnostic Sciences, College of Dentistry, The University of Tennessee Health Science Center, Memphis, TN, USA; Department of Otolaryngology, College of Medicine, The University of Tennessee Health Science Center, Memphis, TN, USA. Electronic address: Aowosho@uthsc.edu.
² Department of Diagnostic Sciences, College of Dentistry, The University of Tennessee Health Science Center, Memphis, TN, USA.
³ Department of Diagnostic Sciences, School of Dental Medicine, University of Pittsburgh, Pittsburgh, PA, USA.

PMID: 37891121
DOI: 10.1016/j.oooo.2023.07.050

Abstract

Objective: Recent studies have identified recurrent rearrangements of EWSR1 or FUS with NFATC2 in extragnathic simple bone cysts (SBCs). We investigated the presence of EWSR1 or FUS rearrangements and the immunophenotypic expression of NKX2.2 and CD99 in a series of SBCs of the jaw.

Study design: We retrieved 10 cases of SBC of the jaw from the University of Pittsburgh archives. Of the 10 cases, we were able to evaluate 8 by immunohistochemistry for CD99 and NKX2.2 and 7 by fluorescence in situ hybridization (FISH) for EWSR1 and FUS rearrangement using EWSR1 and FUS break-apart probes.

Results: All 8 cases evaluated by immunohistochemistry expressed CD99 but were negative for NKX2.2, and all 7 cases assayed using FISH were negative for EWSR1 and FUS rearrangements.

Conclusions: In contrast to the SBC of extragnathic sites, we found no presence of EWSR1 and FUS rearrangements by FISH in the SBC of the jaw, suggesting that this entity may be etiologically/molecularly distinct and reflects a non-neoplastic reactive process. However, as these lesions tend to be paucicellular, FISH may not be the appropriate technique for identifying EWSR1/FUS fusions. Other techniques should be used to evaluate them in future studies.