Does ILC look like IDC on biopsy when it has invaded the duct?

Icantri

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my biopsy said I had Ductal carcinoma with lobular features. They diagnosed me invasive Ductal carcinoma. I just got my final path results online and it said that the lesion was lobular and that there is extensive LCIS.

So what I am wondering is it likely that the cancer was lobular all along, and when they biopied my lump the needle happened to hit part of the tumor that had spread beyond the lobule and into the duct?

Or is it more likely that I have features of both?

And does it even matter?

At any rate my breast sounded like a big old mess of 50% fibrous tissue/50% fatty breast tissue, extensive LCIS and multifocal cancer. I am so happy I chose mastectomy over the lumpectomy they recommended.

Icantri

more info from path report:

Final diagnosis

-Multifocal invasive mammary carcinoma with lobular cytology, grade 2 of 3

- Lobular carcinoma in situ

- Prior biopsy site changes present

- Background breast tissue with fibrocystic changes including usual ductal hyperplasia and columnar cell hyperplasia without atypia

Meow13

I am not sure at first biopsy said I had 2 distinct lobular invasive tumors. And mastectomy pathology said one was IDC with lobular features. But 95% confidence separate tumors not really multi focal. I am glad I mastectomy and no radiation.

ShetlandPony

Icantri, if the cancer originated in the lobule and spread to the duct, I think it would still look like lobular. The pathologist names the type based on the appearance of the cells. The hallmark of ILC is loss of, or sometimes present but aberrant, e-cadherin. Does your report mention e-cadherin? If not, you could ask the patholgist.

Does the type matter? IDC-L (invasive ductal carcinoma with lobular features) behaves more like ILC than IDC in terms of hormone receptor positivity, tumor foci, need for re-excision, and nodal status. Since you had a mastecomy, the last three have been addressed. What were your ER and PR percentages, and what endocrine therapy will you be getting? There is not much difference in therapy options for ILC vs. IDC at present, but hopefully we will know more in the future. Some are looking into whether tamoxifen is equally effective for IDC and ILC.

My comments are based on my notes from the 2016 ILC symposium in Pittsburgh.