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?

Question

Accepted Answer

B. Grade II (Moderately differentiated). ## 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.

Answer

A. Grade III (Poorly differentiated)

Answer

C. Grade I (Well-differentiated)

Answer

D. Cannot be determined without Ki-67 index

Explanation

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