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Adamantinoma-like Ewing Sarcoma (ALES) May Harbor FUS Rearrangements : A Potential Diagnostic Pitfall.

Authors :
Palsgrove DN
Foss RD
Yu W
Garcia J
Rooper LM
Rekhtman N
Antonescu C
Gagan J
Agaimy A
Bishop JA
Source :
The American journal of surgical pathology [Am J Surg Pathol] 2023 Nov 01; Vol. 47 (11), pp. 1243-1251. Date of Electronic Publication: 2023 Jul 27.
Publication Year :
2023

Abstract

Adamantinoma-like Ewing sarcoma (ALES) is a rare malignancy currently considered a variant of Ewing sarcoma with most known cases harboring EWSR1 rearrangements. Herein we present a series of 6 cases of EWSR1 -negative ALES. The tumors arose in the sinonasal tract (n=3), major salivary glands (submandibular gland=1; parotid=1), and anterior mediastinum (n=1) in patients ranging from 25 to 79 years of age. Most tumors were basaloid in appearance, growing in large nests separated by interlobular fibrosis without overt squamous pearls. However, 1 case closely resembled a well-differentiated neuroendocrine tumor with uniformly round nuclei, eosinophilic cytoplasm, and trabecular architecture. All cases were diffusely positive for pan-cytokeratin, p40 or p63, and CD99. A subset of cases showed diffuse reactivity for synaptophysin, including 1 sinonasal tumor which also demonstrated sustentacular S100 protein expression. Molecular testing showed FUS rearrangements in all cases. Gene partners included known ETS family members FEV (n=2) and FLI1 (n=1). Our results expand the molecular diagnostic considerations for ALES to include FUS rearrangements. We also show that ALES may harbor FUS :: FLI1 fusion, which has not been previously reported in the Ewing family of tumors. Furthermore, ALES may show unusual histologic and immunophenotypic features that can overlap with olfactory carcinoma including S100-positive sustentacular cells. ALES should be considered in the diagnostic differential of small round cell tumors and tumors with neuroendocrine differentiation with immunohistochemical workup to include p40 and CD99/NKX2.2.<br />Competing Interests: Conflicts of Interest and Source of Funding: Funded by the Jane B. and Edwin P. Jenevein M.D Endowment for Pathology at UT Southwestern Medical Center. The authors have disclosed that they have no significant relationships with, or financial interest in, any commercial companies pertaining to this article.<br /> (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Details

Language :
English
ISSN :
1532-0979
Volume :
47
Issue :
11
Database :
MEDLINE
Journal :
The American journal of surgical pathology
Publication Type :
Academic Journal
Accession number :
37494548
Full Text :
https://doi.org/10.1097/PAS.0000000000002100