I wanted to take some time to write about one of the most challenging areas in breast pathology and one that I receive countless questions about–distinguishing atypical ductal hyperplasia (ADH) from ductal carcinoma in situ (DCIS). While this may seem like an academic issue that doctors argue about it has MAJOR clinical implications for patients.

Atypical ductal hyperplasia refers to a proliferation of cells in the breast ducts that doesn’t quite meet all of the criteria for low grade ductal carcinoma in situ. While I am para-phrasing, this is basically the definition that exists in the pathology literature. The problem for pathologists is that this definition is very subjective. There have been several studies that show that pathologists frequently do not agree on whether a certain biopsy is ADH or DCIS (if you are interested I can email you the references). The bigger problem for patients is that your doctors will recommend completely different treatments depending on whether your pathologist diagnosis ADH or DCIS.

For example, if you have a lumpectomy and you receive a diagnosis of ADH then your surgery is complete; your pathologist doesn’t need to comment on the surgical margins and radiation therapy is not recommended for ADH. However, if your pathologist makes a diagnosis of DCIS then you are diagnosed with “breast cancer” and your surgeon will want to know 1) if he/she got clear margins on the DCIS and you may need additional surgery; 2) your medical oncologist may ask the pathologist to determine if your DCIS is estrogen receptor positive so you can receive anti-estrogen therapy; and 3) you may be referred to a radiation therapist to get radiation to your breast.

So you can see why this distinction is so important to patients. If you are confronted with a diagnosis of ADH or DCIS, make sure that you find out if your pathologist has a lot of experience in breast pathology or get a second opinion on your biopsy. It can make a significant difference in what treatment, if any, your doctors recommend.

If you are interested, I have a tutorial on breast pathology and in the first installment I talk about ADH and DCIS and show some images of how they can look very similar under the microscope.

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