- DCIS surrounding an Infiltrating Ductal Ca (or within)
- Definition = DCIS involving > 25% of the area of the invasive tumour, and also present at edge of tumour
- Can be predicted by area of microcalcifications ≥ 30mm (+ mass) on pre-op mammogram
- More common in tumours in younger women
- EIC is possibly predictor of local recurrence
- x 3-4 if EIC in tumour, but studies did not take positive margins into account
- If clear margins, no increased rate of local recurrence
- Tumours with EIC more likely to have residual tumour burden after WLE
- Nodal involvement is rare
- 1-2% rate of +ve nodes (from a missed microinvasive focus)