## Histological Types of Breast Carcinoma **Key Point:** Invasive Ductal Carcinoma (IDC), also called Invasive Carcinoma of No Special Type (NST), accounts for approximately 70–80% of all invasive breast cancers. ### Frequency Distribution | Histological Type | Frequency | 5-Year Survival | |---|---|---| | Invasive Ductal Carcinoma (NST) | 70–80% | 60–70% | | Invasive Lobular Carcinoma | 10–15% | 65–75% | | Mucinous (Colloid) Carcinoma | 2–3% | 80–90% | | Tubular Carcinoma | 2–3% | 85–95% | | Papillary Carcinoma | 1–2% | >90% | | Medullary Carcinoma | 3–5% | 70–80% | **High-Yield:** IDC (NST) is the default diagnosis when no special histological pattern is identified. It is the most common, most aggressive, and has the worst prognosis among common types. ### Clinical Pearl The special types (mucinous, tubular, papillary) are **rare but favourable** — they have better prognosis than IDC. Conversely, IDC and Invasive Lobular Carcinoma (ILC) are more common and carry intermediate to worse prognosis. ### Key Distinguishing Features - **IDC (NST):** Infiltrating nests and cords of cells without a specific pattern; high mitotic activity; often high grade. - **ILC:** Single-file infiltration of cells; often lower grade; higher risk of bilaterality and contralateral breast involvement. - **Mucinous:** Tumour cells floating in abundant mucin; low grade; excellent prognosis. - **Tubular:** Well-formed tubules; low grade; excellent prognosis. **Mnemonic: IDCNST** — **I**nvasive **D**uctal **C**arcinoma **N**o **S**pecial **T**ype — the commonest, most aggressive breast cancer. [cite:Robbins 10e Ch 24]
Sign up free to access AI-powered MCQ practice with detailed explanations and adaptive learning.