Pathological Subtypes of Breast Cancer

There are over 12 subtypes of breast cancer - though most of them are rare
- Invasive carcinoma (No Special Type) is by far the most common followed by Invasive lobular
- the remaining subtypes are quite rare

1) Invasive carcinoma: No Special Type
- majority 70-80%
Subtypes:
- Luminal A (ER +ve, HER2/neu -ve)
- Luminal B (Triple +ve)
- Normal Breast-Like (ER +ve, HER2/neu -ve)
- Basal-Like (ER -ve, PR -ve, HER2/neu -ve)
- HER2 positive (ER -ve, HER2/neu +ve; associated with brain mets)

2) Invasive Lobular Carcinoma
- increased bilateral

3) Medullary Carcinoma
- 6th decade of life
- slightly better prognosis than NST carcinomas despite negative histological features
- high nuclear grade, aneuploidy, absence of hormone receptors, high proliferative rate
- rapidly growing with smooth borders and thereforeon imaging can resemble a benign lesion

4) Mucinous (Colloid) Carcinoma
- older women
- grow slowly
- ER +ve, LN mets uncommon
- slightly better prognosis vs. NST

5) Invasive Papillary Carcinoma
- <1% of invasive ca
- ER +ve
- favorable prognosis
- much different outcome compared to micropapillary carcinoma

6) Micropapillary Carcinoma
- ER -ve, HER2/neu _ve
- LN mets
- poor prognosis

7) Metaplastic carcinoma
- rare type of breast cancer (<1% of cases)
- Matrix-producing carcinomas
- Triple negative
- LN mets infrequent but poor prognosis

Source:
Robbins