An Overview of Papillary Carcinoma of the Breast

Papillary carcinoma of the breast, also known as intraductal papillary carcinoma, is a rare type of breast cancer that accounts for only 0.5% of all new cases of invasive breast cancers. It is defined by finger-like projections called papules, which can be seen when cells are examined under a microscope. Many papillary tumors are not cancerous; these are called papillomas. When papillary tumors are malignant, it is because they include both in situ cells, which haven’t spread outside the duct, and invasive cells that have begun to spread.

Papillary carcinomas are most often diagnosed in women who have already gone through menopause. Interestingly, diagnoses of papillary carcinoma in men appear to be higher than that of other types of male breast cancer.

While concerning, papillary carcinoma of the breast is less likely to affect the lymph nodes, is more responsive to treatment, and may offer a better prognosis than other types of invasive ductal cancers. 

Symptoms

Some papillary carcinomas may create a lump large enough to feel with the fingers, and that may cause breast tenderness. Discharge is also possible. Often, papillary carcinomas don't cause any symptoms and are not caught with breast self-examination.

Rather, papillary carcinoma is usually found during a routine mammogram (breast imaging), appearing as a well-defined mass behind or just beyond the areola.

Routine breast screening in the form of annual mammograms is the best way to identify papillary breast carcinoma before any symptoms are evident. 

Causes

Anyone can develop papillary carcinoma of the breast; researchers do not really know what causes it to develop.

Diagnosis

Papillary breast cancer is diagnosed much like other types of breast cancer. Imaging alone is not enough to make a diagnosis of papillary breast carcinoma, so mammograms, ultrasound, and/or breast magnetic resonance imaging (MRI) are done in conjunction tissue biopsy.

A tissue biopsy for papillary breast carcinoma involves taking a sample of the tumor and examining it under a microscope. The cancer cells' finger-like appearance is what distinguishes them from cells that would be apparent in other types of breast cancer.
Papillary carcinoma is often found with ductal carcinoma in situ (DCIS), which is a type of early stage breast cancer confined to a milk duct.

Misdiagnosis

Papillary carcinoma is sometimes misdiagnosed as intraductal papilloma or papillomatosis. 

Intraductal papilloma is a noncancerous condition in which a tiny, wart-like growth in breast tissue punctures a duct. Intraductal papillomas grow inside the breast's milk ducts and may cause benign nipple discharge.

Papillomatosis is a kind of hyperplasia, another noncancerous condition that may occur in the ducts and cause cells to grow larger and faster than normal.

Having one or more intraductal papillomas, or papillomatosis, slightly increases your risk of developing breast cancer.

Treatment

Most cases of papillary carcinoma are low-grade, slow-growing cancers. Many do not spread very far beyond their original site. That said, treatment is important. Options depend on various features of the cancer, including:

• Size of the tumor (papillary breast tumors are often small)
• Tumor grade
• Hormone receptor status
• HER2 status

Surgery

Lumpectomy, removal of the non-invasive cancer with a margin of surrounding tissue, or mastectomy, removal of all breast tissue (including the nipple and the areola) may be considered.

Drug Therapies

Chemotherapy destroys cells and may be offered depending on tumor grade, hormone receptor and Her2 status, and if lymph nodes are affected.

Hormone therapy drugs, on the other hand, can block the effect of estrogen on cancer cells. Papillary breast cancer cells will be tested to determine if estrogen binds to them. If it does, hormone therapy can be helpful.

Targeted therapies also block the growth and spread of cancer cells. The most widely used target therapy is Herceptin (trastuzumab). Herceptin has been found to be very effective for treating HER2-positive breast cancers. It is not helpful for HER2-negative cancers, however.

Finally, bisphosphonates—bone-building drugs found to help reduce the risk of cancer recurrence in post-menopausal women—can also be helpful in preventing cancer cells from spreading. 

A Word From Verywell

Cancer support groups are a great resource for finding people who have first-hand experience with a breast cancer diagnosis. Just be prepared that you may not meet someone else who has papillary carcinoma of the breast, given how rare it is. Connecting with others coping with breast cancer diagnosis and going through treatment can be invaluable. When it comes to discussing the specifics of your condition, however, your best resource remains your healthcare team.