Synonym: invasive ductal carcinoma with predominant intraductal component (WHO)
Features of infiltrating carcinoma with extensive DCIS:
(1) presence of invasive carcinoma
(2) a significant proportion of the region involved by the invasive carcinoma consists of DCIS.
(3) DCIS is present beyond the area of invasive tumor.
where:
• The criteria for what constitutes a significant proportion of the DCIS is not clear cut.
• Tavassoli refers to DCIS comprising > 25% of the invasive carcinoma, but this would also include a focus of DCIS with microinvasion.
• Schnitt et al use DCIS as "moderate or marked" within the tumor.
• Matsukuma et al reported that tumors with DCIS and less than 20% invasion had better survivals than those with >= 20%. The problem here is determining the relative volume for those tumors that are not discreet lesions.
• In addition, the amount of DCIS beyond the area of invasion is somewhat subjective. A single small duct would probably not qualify.
Recurrence is more likely if:
(1) the margins of excision are positive
(2) the DCIS is Tavassoli Grade III/III (Schnitt et al)
Limitations:
• There is likely to be some inter-pathologist variation in the use of this term.
• In the cases I have seen, a key factor is whether I think the process is an infiltrating carcinoma with DCIS, or DCIS with infiltrating carcinoma.
