Tricogerminoma: una neoplasia con diferenciación folicular y una morfología característica

Lozano-Masdemont, Belén; Rodríguez-Soria, V.J.; Gómez-Recuero-Muñoz, L.; Parra‐Blanco, Verónica

doi:10.1016/j.ad.2016.04.013

Cited by 2 publications

(2 citation statements)

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“…Further, immunohistochemical investigations revealed notably that CK5/6 as well as BCL-2 might contribute to this diagnosis by confirming the presence of so-called 'cell balls' [16,17]. To the best of our knowledge, up to now, only 30 trichogerminoma cases have been reported in the literature [15][16][17][18][19][20][21][22][23], a finding which might be explained by the rarity of this entity but also by the lack of established diagnostic criteria [19]. Trichogerminoma is not yet included in the fourth edition of the WHO Classification of Skin Tumours [13] and is regarded by most of the authors as a variant of trichoblastoma [19,47].…”

Section: Discussionmentioning

confidence: 99%

“…Trichogerminoma is a rare follicular neoplasm characterized by an immature morphology and 'cell balls' formation. Since the first description by Sau et al in 1992 [15], only 30 cases have been previously reported in the literature [15][16][17][18][19][20][21][22][23] and no consensual diagnostic criteria have yet been determined. Moreover, whether such a tumour entity exists and/or constitutes a variant of trichoblastoma has been a matter of debate [19].…”

Section: Introductionmentioning

confidence: 99%

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

Kervarrec

Pissaloux

Poilane

et al. 2022

The Journal of Pathology

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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.

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