Sacral Nerve Hemangiopericytoma: A Rare Case and Review of the Literature
Bibliographic record
Abstract
Introduction: Hemangiopericytomas usually occur in the soft tissue and skeletal system. They rarely present in the spinal canal as a primary tumor. There are several case reports describing primary spinal hemangiopericytomas of the cervical and thoracic spine; however, there are only 3 reports of sacral hemangioperictyomas (Liu, 2013; McMaster, 1975; Zhao, 2007). We report an extremely rare presentation of a primary spinal hemangiopericytoma arising from the S2 nerve root with local bony destruction of the sacrum. Case Report: A 52 year-old male presented with low back pain and left lower extremity numbness and tingling. MRI showed a 5.2 cm x 5.7 cm sacral mass, and CT showed local bony destruction of the sacrum. He complained of left S2 pain. The patient was taken for resection of the tumor. A gross total resection was achieved from a posterior midline approach. A corridor lateral to the sacral nerves allows resection of the ventral portion of the tumor. A gross total resection was achieved with a small residual adherent to the left S2 nerve root. Pathology confirmed the tumor to be a grade II hemangiopericytoma. Adjuvant radiotherapy was recommended due to the residual.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.006 | 0.005 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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 itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".