Breast Pathology

Ed Uthman, MD Laboratory Medical Director OakBend Medical Center

Ed Uthman, MD
Laboratory Medical Director OakBend Medical Center

No cancer diagnosis is made without a biopsy, which is a small sample of the patient’s tumor, typically removed by a radiologist or surgeon. The physician who examines the biopsy is a pathologist. Following college and medical school, the budding pathologist undertakes a minimum of four years of residency training to become board certified and enter practice.

Contrary to the popular image, few pathologists perform autopsies on dead bodies. Modern pathologists are mostly concerned with the care of living patients. Interpreting biopsies is both art and science. In addition to determining the patient has cancer, the pathologist must classify the tumor into one of several categories and ascertain how aggressive the cancer is.

Entire textbooks have been written on breast pathology, so there is no way to give it exhaustive coverage here. However, there is a current issue with breast biopsies that the public needs to be aware of. The most common type of breast cancer is invasive ductal carcinoma. The cells that become malignant begin as normal cells lining the tiny ducts that convey milk from where it is produced to the nipple. When one of these cells turns malignant, it loses its normal inhibition to grow and divide. It multiplies uncontrollably, making millions of other cells that escape the duct, produce a lump, invade nearby tissues, get into lymph vessels and spread to lymph nodes and other organs. The diagnosis of invasive ductal carcinoma is relatively straightforward, and pathologists almost always agree with each other on the diagnosis in a given case.

Advancements in medical imaging have given us the ability to identify a subset of patients who do not yet have invasive ductal carcinoma. In this group, the abnormal cells are dividing and multiplying, but they have not yet become malignant enough to escape their duct and invade other tissues.

There is spectrum of abnormality that these “intraductal” cell proliferations exhibit. The most benign diagnosis in this spectrum is “duct hyperplasia.” The most malignant is “ductal carcinoma in situ,” or DCIS. In between the two is an intermediate grey zone, dubbed “atypical duct hyperplasia,” or ADH. Most physicians and patients see the word “carcinoma” in DCIS and view that as “cancer,” while the ADH diagnosis is something less than or better than cancer. The DCIS patient may be offered a lumpectomy or mastectomy, while the ADH patient is followed and observed. This approach is logical in concept, but in reality, there is a significant problem with categorizing a given biopsy. It turns out that for these intraductal lesions, the distinction between ADH and DCIS is poorly reproducible, and disagreements between pathologists are common.

The takeaway lesson is that it is always a good idea to get a second pathologist’s opinion when presented with a diagnosis of DCIS or ADH. Any disagreement needs to be resolved before treatment, not after.