Pleomorphic xanthoastrocytoma: report of two cases with unconventional clinical presentations
Bibliographic record
Abstract
AIMS: Pleomorphic xanthoastrocytoma (PXA) is a rare astrocytic neoplasm with a relative circumscribed architecture that typically arises superficially in the cerebral hemispheres of teenagers and young adults. Our aim is to highlight unconventional clinical presentations of this distinct neoplasm. MATERIALS AND METHODS: We report two cases of PXA with unconventional clinical features, including clinical, pathologic, and immunohistochemical features. RESULTS: The first case developed in the left frontal lobe of a 20-year-old female with neurofibromatosis type 1 (NF1). Focal anaplastic features were present. The neoplastic cells were immunoreactive for GFAP, S-100 protein and focally for synaptophysin, with a MIB-1/Ki-67 proliferative labelling index of 16%. The second case developed in a 39-year-old female as a suprasellar neoplasm. The neoplastic cells expressed GFAP, S-100 protein and focally CD34. The adenohypophysis was positive for synaptophysin and pituicytes for TTF1. Molecular studies were negative for BRAF (V600E) mutation in both cases. CONCLUSION: PXA is a distinct circumscribed neoplasm that may present in unexpected locations or clinical backgrounds. Neuropathologists must be aware of these unconventional presentations in order to provide a precise diagnosis leading to appropriate treatment.
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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 | 0.001 | 0.005 |
| Meta-epidemiology (narrow) | 0.003 | 0.002 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.002 | 0.002 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.001 | 0.003 |
| Research integrity | 0.005 | 0.002 |
| Insufficient payload (model declined to judge) | 0.002 | 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".