A 58-year-old woman from Mumbai undergoes mastectomy for a 2.5 cm breast carcinoma. Histopathology reveals invasive ductal carcinoma with the following findings: mitotic count 18 per 10 high-power fields, nuclear pleomorphism (moderate), and tubule formation in 25% of the tumour. Immunohistochemistry shows ER+, PR+, HER2−. What is the Nottingham Histological Grade (Bloom–Richardson Grade) of this tumour?

Explanation

## Nottingham Histological Grade (Bloom–Richardson Grade) **Key Point:** The Nottingham grade is based on three morphological components, each scored 1–3: | Component | Score 1 | Score 2 | Score 3 | |-----------|---------|---------|----------| | **Tubule Formation** | >75% | 10–75% | <10% | | **Nuclear Pleomorphism** | Small, uniform | Intermediate | Large, irregular | | **Mitotic Count** | 0–7 per 10 HPF | 8–14 per 10 HPF | ≥15 per 10 HPF | **Grading:** - **Grade I**: Total score 3–5 (well-differentiated) - **Grade II**: Total score 6–7 (moderately differentiated) - **Grade III**: Total score 8–9 (poorly differentiated) **In this case:** - Tubule formation 25% → Score 2 (10–75%) - Nuclear pleomorphism moderate → Score 2 - Mitotic count 18 per 10 HPF → Score 3 (≥15) - **Total score: 2 + 2 + 3 = 7 → Grade II** **Clinical Pearl:** Grade II tumours have intermediate prognosis and are the most common grade in clinical practice. Hormone receptor status (ER+, PR+) indicates luminal subtype but does not affect histological grading.