Undifferentiated Round Cell Sarcoma With CRTC1::SS18 Fusion: Expanding Clinicopathologic Features of a Rare Translocation Sarcoma With Prominent Desmoplastic Stroma.

Autor:	Warmke LM; Department of Pathology, Indiana University School of Medicine, Indianapolis, Indiana. Electronic address: lwarmke@iu.edu., Strike SA; Department of Orthopaedic Surgery, The Johns Hopkins Hospital, Baltimore, Maryland., Fayad LM; Department of Radiology and Radiological Science, The Johns Hopkins Hospital, Baltimore, Maryland., Ahlawat S; Department of Radiology and Radiological Science, The Johns Hopkins Hospital, Baltimore, Maryland., Liu YJ; Department of Laboratory Medicine and Pathology, University of Washington School of Medicine, Seattle, Washington., Mata DA; Foundation Medicine, Inc, Cambridge, Massachusetts., Rooper L; Department of Pathology, The Johns Hopkins Hospital, Baltimore, Maryland., Baraban E; Department of Pathology, The Johns Hopkins Hospital, Baltimore, Maryland., Zou YS; Department of Pathology, The Johns Hopkins Hospital, Baltimore, Maryland., Gross JM; Department of Pathology, The Johns Hopkins Hospital, Baltimore, Maryland.
Jazyk:	angličtina
Zdroj:	Modern pathology : an official journal of the United States and Canadian Academy of Pathology, Inc [Mod Pathol] 2024 Sep; Vol. 37 (9), pp. 100555. Date of Electronic Publication: 2024 Jul 06.
DOI:	10.1016/j.modpat.2024.100555
Abstrakt:	Undifferentiated round cell sarcomas (URCS) represent a diverse group of tumors, including conventional Ewing sarcoma, round cell sarcoma with EWSR1/FUS-non-ETS fusions, CIC-rearranged sarcoma, and sarcoma with BCOR alterations. Since 2018, 3 cases of URCS with a novel CRTC1::SS18 gene fusion have been reported in the literature. Herein, we report 3 additional cases of CRTC1::SS18 sarcoma, thereby doubling the number of described cases and expanding the clinicopathologic features of this rare translocation sarcoma. Together with the previously reported cases, we show that the male-to-female ratio is 1:2 with a median age of 34 years (range, 12-42 years). Tumors occurred primarily in intramuscular locations involving the lower extremity. Histologically, all tumors contained uniform round-to-epithelioid cells with a moderate amount of eosinophilic cytoplasm growing in sheets and nests with prominent desmoplastic stroma reminiscent of desmoplastic small round cell tumor. Immunohistochemical results were nonspecific, demonstrating variable expression of CD99 (patchy), ALK, GATA3, and cyclin D1. RNA sequencing revealed CRTC1::SS18 gene fusions in all cases, involving exons 1 to 2 of CRTC1 (the 5' partner gene) on chromosome 19 and either exon 2 or exon 4 of SS18 (the 3' partner gene) on chromosome 18. The clinical course was variable. Although 1 previously reported case demonstrated aggressive behavior with a fatal outcome, 2 others had a relatively indolent course with gradual growth for 6 to 7 years prior to resection. Two cases developed metastatic disease, including 1 case with bilateral lung metastasis and 1 with locoregional spread to a lymph node. By analyzing the clinicopathologic features, we aimed to improve recognition of this rare translocation sarcoma to better understand its biologic potential, optimize patient management, and expand the current classification of URCS. (Copyright © 2024 United States & Canadian Academy of Pathology. Published by Elsevier Inc. All rights reserved.)
Databáze:	MEDLINE
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