Best Practices Recommendations in the Application of Immunohistochemistry in the Bladder Lesions
Bibliographic record
Abstract
The bladder working group of the 2013 International Society of Urologic Pathology (ISUP) Conference on Best Practices Recommendation in the Application of Immunohistochemistry (IHC) in Urologic Pathology discussed 5 settings in which IHC is commonly used in clinical practice. With regard to markers for urothelial differentiation, the committee found that there is no ideal marker or established panel to confirm urothelial differentiation. On the basis of the differential diagnostic consideration, positivity for GATA3, CK20, p63, and either high-molecular weight cytokeratin (HMWCK) or cytokeratin (CK)5/6 is of value in proving urothelial differentiation in the appropriate morphologic and clinical context. With regard to the role of IHC in the distinction of reactive atypia from urothelial carcinoma in situ, the committee recommended that morphology remains the gold standard in this differential diagnosis and that, at best, the IHC panel of CK20/p53/CD44(s) has potential utility but is variably used and has limitations. The immunostaining pattern must be interpreted with strict morphologic correlation, because overreliance on IHC may be misleading, particularly in the posttreatment setting. IHC has no role in the distinction of dysplasia versus carcinoma in situ and in the grading of papillary urothelial carcinoma. IHC may have a limited but distinct role in staging of bladder cancer. In a subset of cases, depending on the clinical and histologic context, broad-spectrum cytokeratins (to identify early or obscured invasion) and desmin (distinction of muscle from desmoplasia and to highlight muscle contours for subclassification) may be helpful. Limited experience and conflicting data preclude smoothelin or vimentin to be recommended routinely for subclassifying muscle type at this time. In the workup of a spindled cell proliferation of the bladder and in limited specimens, we recommend an immunohistochemical panel of 6 markers including ALK1, SMA, desmin, cytokeratin (AE1/AE3), and p63 with either of HMWCK or CK5/6. Currently, there are no prognostic immunohistochemical or molecular studies that are recommended to be routinely performed on biopsy or resection specimens.
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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 | 0.136 | 0.230 |
| Meta-epidemiology (narrow) | 0.003 | 0.002 |
| Meta-epidemiology (broad) | 0.004 | 0.008 |
| Bibliometrics | 0.012 | 0.007 |
| Science and technology studies | 0.004 | 0.007 |
| Scholarly communication | 0.011 | 0.008 |
| Open science | 0.018 | 0.010 |
| Research integrity | 0.025 | 0.027 |
| Insufficient payload (model declined to judge) | 0.010 | 0.012 |
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".