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Recurrent FOXK1::GRHL and GPS2::GRHL fusions in trichogerminoma.

Authors :
Kervarrec T
Pissaloux D
Poilane J
Tirode F
Tallet A
Collin C
Tallegas M
Berthon P
Gaboriaud P
Sohier P
Calonje E
Luzar B
Goto K
Cokelaere K
Lamant L
Balme B
Wild R
Neuville A
Deschamps L
Auberger E
Paumier V
Bonte H
Moulonguet I
Plantier F
Cales V
Pinsolle V
Roblet D
Dupuy F
Dallot A
Seris A
Jouary T
Houben R
Schrama D
Hesbacher S
Macagno N
Battistella M
Cribier B
Vergier B
de la Fouchardière A
Jullie ML
Source :
The Journal of pathology [J Pathol] 2022 May; Vol. 257 (1), pp. 96-108. Date of Electronic Publication: 2022 Mar 28.
Publication Year :
2022

Abstract

We report 21 cases of trichogerminoma harbouring previously undescribed FOXK1::GRHL1/2 or GPS2::GRHL1/2/3 in-frame fusion transcripts. Microscopic examination of a preliminary set of five cases revealed well-delimitated tumours located in the dermis with frequent extension to the subcutaneous tissue. Tumours presented a massive and nodular architecture and consisted of a proliferation of basaloid cells. A biphasic pattern sometime resulting in tumour cell nests ('cell balls') was present. Immunohistochemistry demonstrated the expression of cytokeratins (CKs) 15, 17, and PHLDA1. In addition, numerous CK20-positive Merkel cells were detected. RNA sequencing (RNA-seq) revealed a FOXK1::GRHL1 chimeric transcript in three cases and a FOXK1::GRHL2 fusion in two cases. In a second series for validation (n = 88), FOXK1::GRHL1/2 fusion transcripts were detected by RT-qPCR or FISH in an additional 12 trichogerminomas and not in any other follicular tumour entities or basal cell carcinoma cases (n = 66). Additional RNA-seq analysis in trichogerminoma cases without detected FOXK1::GRHL1/2 rearrangements revealed GPS2::GRHL1 fusion transcripts in two cases, GPS2::GRHL2 in one case, and GPS2::GRHL3 fusion transcript in one case. Therefore, our study strongly suggests that GRHL1/2/3 gene rearrangements might represent the oncogenic driver in trichogerminoma, a subset of follicular tumours characterized by immature features and numerous Merkel cells. © 2022 The Pathological Society of Great Britain and Ireland.<br /> (© 2022 The Pathological Society of Great Britain and Ireland.)

Details

Language :
English
ISSN :
1096-9896
Volume :
257
Issue :
1
Database :
MEDLINE
Journal :
The Journal of pathology
Publication Type :
Academic Journal
Accession number :
35049062
Full Text :
https://doi.org/10.1002/path.5872