## Nottingham/Bloom-Richardson Grading System for Breast Carcinoma **Key Point:** This is the most widely used grading system for invasive breast cancer. It uses THREE parameters, NOT four. ### The Three Grading Parameters (Scored 1–3 each, Total 3–9) | Parameter | Score 1 | Score 2 | Score 3 | |-----------|---------|---------|----------| | **Tubule Formation** | >75% tubules | 10–75% tubules | <10% tubules | | **Nuclear Pleomorphism** | Small, uniform nuclei | Intermediate size/variation | Large, markedly irregular | | **Mitotic Count** | Low (0–9 per 10 hpf) | Intermediate (10–19 per 10 hpf) | High (≥20 per 10 hpf) | ### Grade Assignment - **Grade I (Well-differentiated)**: Score 3–5 - **Grade II (Moderately differentiated)**: Score 6–7 - **Grade III (Poorly differentiated)**: Score 8–9 **High-Yield:** Grade I has best prognosis; Grade III has worst prognosis. Grading is independent of tumor size (unlike staging). ### What is NOT Part of Bloom-Richardson Grading - **Lymphocytic infiltration** (tumor-infiltrating lymphocytes, TILs): Assessed separately; NOT part of formal grading - **Stromal response**: Assessed separately; NOT part of formal grading - **Hormone receptor status**: Assessed separately - **HER2 status**: Assessed separately **Clinical Pearl:** TILs and stromal response are prognostic factors but are NOT components of the Bloom-Richardson score. They are evaluated independently for prognostic stratification.
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