Increased Detection of Metastatic Melanoma in Pediatric Sentinel Lymph Node Biopsies Using RT-PCR on Paraffin-embedded Tissue
Bibliographic record
Abstract
Sentinel lymph node (SLN) biopsy has become integral in the staging of patients with melanoma, and entails detailed histologic examination with immunohistochemistry. Reverse transcriptase-polymerase chain reaction (RT-PCR) for tyrosinase transcripts has been used to increase sensitivity but requires a dedicated piece of tissue that does not undergo histologic examination. We developed a nested RT-PCR assay for tyrosinase applicable on paraffin-embedded tissue and applied this to a series of SLNs from pediatric patients with melanoma. Thirty-six SLNs from 4 females and 4 males were included in the study. Eight lymph nodes with reactive changes were included as controls. SLNs were examined histologically and immunohistochemically for S100, tyrosinase, and MART1. Seven patients had between 1 and 4 morphologically-positive SLNs and one patient had negative SLNs (HISTO+; 12/36, 33%). Three lymph nodes were excluded from molecular analysis owing to inadequate RNA, and 29 of the remaining 33 nodes were positive (MOL+; 88%). All patients had at least 1 SLN positive by RT-PCR. Twelve were HISTO+/MOL+; 17 were HISTO-/MOL+; and 4 were HISTO-/MOL-. All control lymph nodes were negative for tyrosinase transcripts. The application of RT-PCR for tyrosinase to paraffin-embedded tissue significantly increased the number of positive SLNs and upstaged one patient from negative to positive. The prognostic implications of such findings require further investigation, especially in the pediatric age group. Nonetheless, this technique provides a useful tool to determine the clinical significance of RT-PCR positivity in melanoma SLNs.
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How this classification was reachedexpand
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 | 0.000 | 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 | 0.000 |
| 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 itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, 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".