Expanding the Spectrum of Intraosseous Rhabdomyosarcoma
Why this work is in the frame
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Bibliographic record
Abstract
Primary intraosseous rhabdomyosarcomas (RMSs) are extremely rare. Recently 2 studies reported 4 cases of primary intraosseous RMS with EWSR1/FUS-TFCP2 gene fusions, associated with somewhat conflicting histologic features, ranging from spindle to epithelioid. In this study we sought to further investigate the pathologic and molecular abnormalities of a larger group of intraosseous RMSs by a combined approach using targeted RNA sequencing analysis and fluorescence in situ hybridization (FISH). We identified 7 cases, 3 males and 4 females, all in young adults, age range 20 to 39 years (median, 27 y). Three cases involved the pelvis, 2 involved the femur and 1 each involved the maxilla and the skull. Molecular studies identified recurrent gene fusions in all 7 cases tested, including: a novel MEIS1-NCOA2 fusion in 2 cases, EWSR1-TFCP2 in 3 cases, and FUS-TFCP2 gene fusions in 1 case. One case showed a FUS gene rearrangement, without a TFCP2 gene abnormality by FISH. The MEIS1-NCOA2-positive cases were characterized by a more primitive and fascicular spindle cell appearance, while the EWSR1/FUS rearranged tumors had a hybrid spindle and epithelioid phenotype, with more abundant eosinophilic cytoplasm and mild nuclear pleomorphism. Immunohistochemically, all tumors were positive for desmin and myogenin (focal). In addition, 4 tumors with TFCP2-associated gene fusions also coexpressed ALK and cytokeratin. In conclusion, our results suggest a high incidence of gene fusions in primary RMSs of bone, with 2 molecular subsets emerging, defined by either MEIS1-NCOA2 or EWSR1/FUS-TFCP2 fusions, showing distinct morphology and immunophenotype. Additional studies with larger numbers of cases and longer follow-up data are required to definitively evaluate the biological behavior of these tumors and to establish their relationship to other spindle cell RMS genetic groups.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it