Recurrent FOXK1::GRHL and GPS2::GRHL fusions in trichogerminoma.
J Pathol
; 257(1): 96-108, 2022 05.
Article
en En
| MEDLINE
| ID: mdl-35049062
ABSTRACT
We report 21 cases of trichogerminoma harbouring previously undescribed FOXK1GRHL1/2 or GPS2GRHL1/2/3 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 FOXK1GRHL1 chimeric transcript in three cases and a FOXK1GRHL2 fusion in two cases. In a second series for validation (n = 88), FOXK1GRHL1/2 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 FOXK1GRHL1/2 rearrangements revealed GPS2GRHL1 fusion transcripts in two cases, GPS2GRHL2 in one case, and GPS2GRHL3 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.
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1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Neoplasias Cutáneas
Límite:
Humans
País/Región como asunto:
Europa
Idioma:
En
Revista:
J Pathol
Año:
2022
Tipo del documento:
Article
País de afiliación:
Francia