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Primary Ewing Sarcoma of the Kidney: Clinicopathologic and Molecular Study of 24 Patients Including a Rare
João Lobo1,2,3, Huiying He4, Raheel Ahmed5
1Department of Pathology, Portuguese Oncology Institute of Porto/Porto Comprehensive Cancer Centre (Porto.CCC).
Abstract:
Primary Ewing sarcoma (ES) of the kidney is rare. We describe the clinicopathologic features of primary renal ES with emphasis on gene fusion partners. A multi-institutional study was conducted to obtain clinicopathologic data on primary ES of the kidney. All tumors with available tissue underwent NGS to determine fusion partners. Twenty-four patients (8 male, 16 female) were identified. Mean age was 33.2 (±12.3). Mean tumor size was 10.5 cm (±4.2). Clinical presentation was available in 21 patients: flank/abdominal pain (13, 61.9%), hematuria (4, 19%), mass (2, 9.5%), hypertension (1, 4.8%), and incidental (1, 4.8%). For 23 nephrectomies, 2 (8.7%) were ypT0 (post-neoadjuvant therapy), 3 (13%) pT1, 15 (65.2%) pT2, 1 (4.4%) pT3, and 2 (8.7%) pT4. Four (16.7%) had metastatic disease at presentation. Of 18 patients with available follow-up, 9 (50%) were alive with disease, 7 (38.9%) alive with no disease, and 2 (11.1%) died of disease (mean follow-up 34 mo). Metastatic disease was documented in 9/18 patients, including lung (3), adrenal (2), bone (2), retroperitoneum (2), liver (2), lymph node (1), and ureter (1). FISH was performed in 14 tumors and real-time quantitative PCR in 1, confirming EWSR1 rearrangements. NGS was performed in 17 tumors, showing EWSR1::FLI1 in 16 (94.1%) and EWSR1::ETV4 in 1. Primary renal ES is a rare neoplasm occurring in a wide age range. Most tumors invaded adjacent tissues. Although they share similar histologic and molecular features with their counterpart in the bone/soft tissue, we document the first case of a rare EWSR1::ETV4 fusion in the kidney.
Insights
Primary renal Ewing sarcoma (ES) is a rare kidney cancer. This study details its features and finds the common EWSR1::FLI1 fusion, plus a rare EWSR1::ETV4 fusion.
Area of Science:
- Oncology
- Genetics
- Pathology
Background:
- Primary Ewing sarcoma (ES) of the kidney is an exceptionally rare malignancy.
- Understanding its clinicopathologic features and molecular drivers is crucial for diagnosis and treatment.
Purpose of the Study:
- To describe the clinicopathologic characteristics of primary renal ES.
- To identify gene fusion partners in primary renal ES using next-generation sequencing (NGS).
Main Methods:
- A multi-institutional study collected data from 24 patients with primary renal ES.
- Tumor tissues underwent fluorescence in situ hybridization (FISH) and NGS to detect gene rearrangements and fusion partners.
- Clinicopathologic data, including presentation, tumor size, stage, and follow-up, were analyzed.
Main Results:
- Twenty-four patients (mean age 33.2 years) were identified, with a mean tumor size of 10.5 cm.
- Common presentations included flank/abdominal pain (61.9%) and hematuria (19%).
- NGS identified EWSR1::FLI1 fusion in 94.1% of tumors and the rare EWSR1::ETV4 fusion in one case, the first reported in the kidney.
Conclusions:
- Primary renal ES is a rare tumor with diverse clinical presentations and significant local invasion.
- While sharing molecular similarities with bone/soft tissue ES, the identification of EWSR1::ETV4 fusion highlights potential unique aspects of renal involvement.
- Further research is needed to understand the implications of these findings for patient outcomes.
