Lobular carcinoma in situ: Clinical sciences

Lobular carcinoma in situ, or LCIS, refers to the non-invasive proliferation of epithelial cells in the terminal ductal lobular unit of the breast. LCIS typically presents as an incidental finding on a breast biopsy done for a separate reason. Further management depends on its histologic type, which includes classic LCIS or other more aggressive variants. Classic LCIS is not considered a malignant finding requiring treatment, but rather a risk indicator for the later development of invasive carcinoma in either breast. On the other hand, more aggressive variants include pleomorphic or florid LCIS, which are more likely to progress into invasive lobular carcinoma.

When assessing a patient that presents with LCIS, first obtain a focused history and physical exam. Patients often discover LCIS from getting a core needle biopsy after an abnormal screening mammogram for a different concern. Your next step is to ask about risk factors, such as age over 40, a personal or family history of breast cancer or genetic mutations, and any usage of hormone replacement therapy, especially for more than five years. On physical exam, LCIS does not usually have any significant findings, but in rare cases, you might be able to palpate a breast lump.

Ok, now that we’ve performed our history and physical exam, let’s take a closer look at the results of the biopsy specimen that showed LCIS in the first place. It’s important to know that LCIS can be broadly classified as classic LCIS and more aggressive variants. While they have a few things in common, they vary by the amount of cellular atypia and proliferation, and therefore the degree of risk for malignancy they carry. So, as you can imagine, each type has a different management.

Alright, let’s start with classic LCIS. So, core needle biopsy might show small, round, uniform, discohesive cells that fill and expand greater than half of the acini of the breast lobule. Although the acini are distended, the overall architecture of the lobule and its basement membrane remains intact. If you see these findings, you have a diagnosis of classic LCIS.

In terms of management, the treatment of classic LCIS is going to largely focus on close surveillance and risk reduction. Follow up in six to twelve months with a clinical exam, and make sure to get yearly screening mammograms. Also, consider adding a breast MRI to the yearly screening. Risk reduction starts with counseling on modifiable lifestyle factors, such as exercise, maintaining a normal BMI, and limiting alcohol use. You’ll also want to talk to your patient about starting chemoprevention, such as a selective estrogen receptor modulator or SERM like Tamoxifen, which can significantly reduce the risk of future breast cancers in both breasts. In the past, many patients actually underwent prophylactic bilateral mastectomy for LCIS, but for most patients, it turns out this is not necessary. However, some patients, either according to their individual values and wishes or because they fall under a high-risk group, may still want to consider this option. High-risk patients include those with known BRCA mutations, significant family histories of breast or ovarian cancer, or prior thoracic radiation at an age of less than thirty. If this is the case, refer them to a breast surgeon for further discussion.

Ok, now that we’ve talked about classic LCIS, let’s go back to the core needle biopsy results to consider more aggressive variants. Let’s say your biopsy shows large, discohesive cells with pleomorphic nuclei, that markedly distend the acini of the breast lobules, and may even have some central necrosis. This is suspicious for a more aggressive variant of LCIS, which is basically LCIS with increased cellular atypia and proliferation. Or, let’s say you have a core needle biopsy result that looks like classic LCIS on histology, but some finding on the diagnostic imaging makes you suspicious that the tissue sample may not fully explain the imaging findings, such as a solid nodule. When this happens it is called radiologic-pathologic discordance. If either of these situations occurs, suspect a more aggressive variant of LCIS. The next step would be to get a surgical biopsy to examine more tissue and confirm the diagnosis.