Encapsulated papillary carcinoma of the breast

by Jason Wasserman MD PhD FRCPC
January 3, 2025

Encapsulated papillary carcinoma is a non-invasive type of breast cancer. “Non-invasive” means that the cancerous cells are confined to where they started and have not spread to nearby breast tissue. This type of tumour behaves similarly to another non-invasive breast cancer called ductal carcinoma in situ (DCIS), which also has a low risk of spreading. Encapsulated papillary carcinoma grows in a way that forms finger-like projections, called “papillae,” inside a cyst-like space. The tumour is surrounded by a fibrous capsule, which helps keep it separate from the surrounding breast tissue. With proper treatment, this tumour generally has a very good outlook.

What are the symptoms of encapsulated papillary carcinoma?

Encapsulated papillary carcinoma may not cause any symptoms in the early stages. When symptoms do appear, they can include a lump in the breast or nipple discharge. However, these symptoms can also be caused by other noncancerous conditions.

What causes encapsulated papillary carcinoma?

The exact cause of encapsulated papillary carcinoma is unknown. Like many other tumours, it likely results from changes in the DNA of breast cells, causing them to grow abnormally.

How is this diagnosis made?

Doctors diagnose encapsulated papillary carcinoma by examining a tissue sample under a microscope. This sample is typically taken through a biopsy, where a small piece of tissue is removed from the lump and studied for signs of cancer. Additional tests, such as imaging scans, may also be used to obtain a clearer picture of the tumour’s size and location.

Your pathology report for encapsulated papillary carcinoma

A pathology report is a medical document prepared by a pathologist, a doctor who specializes in examining tissues under the microscope. This report provides essential details about your diagnosis of encapsulated papillary carcinoma. The type of information included in your pathology report depends on the procedure performed—whether you had a biopsy (a small tissue sample), an endoscopic resection, or surgery to remove the entire tumour. The sections below explain key terms and features commonly found in pathology reports for encapsulated papillary carcinoma, helping you understand your results and their significance for your treatment and prognosis.

Nuclear grade

Pathologists divide encapsulated papillary carcinoma into three levels or grades: low nuclear grade (grade 1), intermediate nuclear grade (grade 2), and high nuclear grade (grade 3). The nuclear grade is determined by looking at a part of the cell called the nucleus and comparing it to the cells normally found in the breast. They also look for the number of mitotic figures (dividing tumour cells).

• Low nuclear grade (grade 1)  – These tumours have small nuclei and few mitotic figures.
• Intermediate nuclear grade (grade 2) – These tumours have larger and more abnormal nuclei and few mitotic figures.
• High nuclear grade (grade 3) – These tumours have very abnormal-looking nuclei, and mitotic figures are found throughout the tumour.

The nuclear grade is important because high grade (grade 3) encapsulated papillary carcinoma is associated with a higher risk of developing invasive cancer compared to a tumour with a low nuclear grade (grade 1).

Invasion

Encapsulated papillary carcinoma with invasion means some tumour cells have spread beyond the fibrous capsule surrounding the tumour. When the cancerous cells move outside of this capsule, they can invade nearby breast tissue, which increases the risk that tumour cells will spread to lymph nodes or other parts of the body. This change can affect treatment options, as doctors may recommend additional treatments to help control or prevent the spread of the tumour.

Margins

In pathology, a margin is the edge or border of tissue removed along with a tumour during surgery. Margins are closely examined under a microscope by a pathologist to see if any cancer cells are present at the cut edge. The status of these margins is important because it helps determine if the entire tumour was removed or if cancer cells may have been left behind in the body.

Margins are typically assessed only after a surgical procedure, such as a resection or excision, which removes the entire tumour. They are usually not described following a biopsy, as biopsies remove only a small sample of tissue, not the whole tumour. The number and type of margins described in your pathology report depend on the size and location of the tumour, as well as the type of tissue removed.

To evaluate margins, the pathologist carefully examines thin slices of the tissue under a microscope. They look closely at the edges to see if tumour cells reach the cut surface. Your pathology report will describe these results as either negative (no cancer cells seen at the margin) or positive (cancer cells present at the margin). If the margin is negative, the report may also mention the exact distance between the closest tumour cells and the cut edge, known as the margin width.

The results of the margin examination are very important for planning your treatment. A positive margin indicates that some cancer cells are likely to remain in the body, thereby increasing the risk of the cancer recurring or progressing. If you have a positive margin, your doctor may recommend further treatment, such as additional surgery to remove any remaining tumour or radiation therapy directed at the area where the positive margin was found. A negative margin, especially with a greater distance from tumour cells to the cut edge, suggests that the cancer has been entirely removed, reducing the likelihood of recurrence.

What stage is encapsulated papillary carcinoma?

Encapsulated papillary carcinoma is assigned a stage called pTis. This is the same stage given to ductal carcinoma in situ (DCIS), a non-invasive form of breast cancer. The pTis stage indicates that the tumour is in situ, meaning it remains confined to its original location without spreading into nearby tissues. This classification highlights that encapsulated papillary carcinoma is an indolent, or slow-growing, tumour with a very low risk of spreading to other areas.

Prognosis

Encapsulated papillary carcinoma generally has a very good outlook, especially if there are no areas of invasive cancer (cancer that has spread beyond the capsule) nearby. In cases of invasion, this tumour can spread to the lymph nodes. If ductal carcinoma in situ (another type of non-invasive breast cancer) is present in the surrounding breast tissue, there may be a higher risk of the tumour coming back. The usual treatment for encapsulated papillary carcinoma involves surgically removing the tumour along with some surrounding tissue to check for any spread and to lower the risk of recurrence. If the tumour has certain features, like more varied cell shapes, higher cell activity, or specific markers (triple-negative or HER2-positive), doctors may treat it more like an invasive breast cancer, which may require additional treatments.

Other helpful resources

American Breast Cancer Foundation

Canadian Breast Cancer Foundation