Usefulness of methylthioadenosine phosphorylase and BRCA‐associated protein 1 immunohistochemistry in the diagnosis of malignant mesothelioma in effusion cytology specimens
Bibliographic record
Abstract
BACKGROUND: The separation of benign from malignant mesothelial proliferations on effusion cytology can be difficult. Loss of methylthioadenosine phosphorylase (MTAP) by immunohistochemistry is an established marker of malignancy in mesothelial proliferations, but to the authors' knowledge largely has been applied only to biopsies. The current study was conducted to determine the usefulness of MTAP immunohistochemistry in the diagnosis of malignant mesothelioma in effusion cytology specimens. METHODS: A total of 21 effusion cytology cases of malignant mesothelioma were stained for MTAP and BRCA-associated protein 1 (BAP1), with 15 reactive mesothelial cytology cases used as a control. Fourteen cases had a paired surgical specimen for comparison, and 7 cases were run for CDKN2A deletion by fluorescence in situ hybridization. RESULTS: Complete loss of MTAP cytoplasmic staining was noted in 7 of 21 effusion samples (33%), and no loss was observed in 11 effusion samples (52%); 11 of these cases had a matching surgical specimen and all 11 specimens demonstrated the same MTAP pattern. Partial loss was observed in 3 effusion specimens (80%, 40%, and 40% intact staining, respectively), but in all 3 the surgical specimen demonstrated 100% staining. None of the 15 reactive mesothelial cytology specimens demonstrated MTAP cytoplasmic loss. CDKN2A FISH demonstrated concordance in 5 of 7 cases (71%). MTAP immunohistochemistry had a sensitivity of 33% and a specificity of 100% for this differential diagnosis. CONCLUSIONS: MTAP staining demonstrated generally good concordance between the cytologic and surgical specimens and appears to be useful in the diagnosis of mesothelioma on effusion specimens. Complete loss of MTAP is a reliable marker of malignancy, but the significance of partial loss of MTAP staining is unclear.
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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 | 0.003 | 0.004 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 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".