ETMR-21. PRIMARY DIFFUSE LEPTOMENINGEAL MELANOMATOSIS (PDLM) ASSOCIATED WITH INTRACRANIAL BLEEDING AND RAPID PROGRESSION IN A CHILD
Bibliographic record
Abstract
Abstract BACKGROUND PDLM is a rare and aggressive disease with limited cases reported worldwide and few cases in the pediatric population. Herein we report on clinical, histologic, and molecular/genetic findings of a young child with PDLM and rapid clinical progression. CASE STUDY A 12-year-old right-handed male presented with two months of intermittent fevers, progressive frontal headaches, lethargy, vomiting, and weight loss, and one month of focal seizures with altered awareness, speech arrest, eye deviation, and tonic posturing. Examination revealed bilateral papilledema and signs of increased intracranial pressure. A brain CT demonstrated increased density of the anterosuperior right frontal lobe and punctate focus of increased density along the left frontal lobe suggestive of hemorrhage. MRI revealed diffuse leptomeningeal thickening and enhancement throughout the brain and spinal cord. At biopsy, the frontal lesion was noted to be grossly abnormal and discolored, and on pathology demonstrated a melanocytic neoplasm infiltrating the subarachnoid space and extending into Virchow-Robin spaces. Tumor cells stained strongly for HMB45, vimentin, Melan-A, and PRAME and were BRAFV600E negative. RNA sequencing was negative for structural variants, Whole exome sequencing revealed a Tier I missense variant in NRAS (c.181C>A) among other copy number variations and loss of heterozygosity. Comprehensive ophthalmologic and dermatologic examinations as well as whole body PET/CT did not reveal any other sites of disease. He was due to commence immunotherapy with combination PD-1/CTLA-4 inhibitors but developed status epilepticus and raised intracranial pressure, warranting ventriculoperitoneal shunt insertion. Three days later, he had further deterioration with altered level of consciousness, hypertension, eye deviation, and vomiting. CT brain revealed large bifrontal hematomas with mass effect and care was redirected to palliation. CONCLUSION PDLM can be challenging to diagnose with a rapidly progressive course. Advanced molecular diagnostics may provide new targets for precision therapy, though overall outcomes remain dismal.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| 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".