Resources for Breast Cancer Care

Mucinous carcinoma of the breast — sometimes called colloid carcinoma — is a rare form of invasive ductal carcinoma (cancer that begins in the milk duct and spreads beyond it into nearby healthy tissue). In this type of cancer, the tumor is composed of abnormal cells that “float” in pools of mucin, a key component of the slimy, slippery substance known as mucus.

Normally, mucus lines most of the inner surface of our bodies, such as our digestive tract, lungs, liver, and other vital organs. Many types of cancer cells — including most breast cancer cells — produce some mucus. In mucinous carcinoma, however, mucin becomes part of the tumor and surrounds the breast cancer cells. Under a microscope, it looks like the cancer cells are scattered throughout pools of mucus.

Research suggests that only about 2-3% of invasive breast cancers are “pure” mucinous carcinomas — meaning that this is the only type of cancer present within the tumor. Mucinous tumor cells tend to behave less aggressively than more typical kinds of invasive ductal cancer. About 5% of invasive breast cancers appear to have a mucinous component within them, with other types of cancer cells present as well. Mucinous carcinoma is extremely rare in men.

Symptoms

Like other types of breast cancer, mucinous carcinoma of the breast may not cause any symptoms at first. Over time, a lump may grow large enough to be felt during breast self-exam or examination by a doctor. As with the other less common types of breast cancer, diagnosing mucinous carcinoma takes special skill and may be detected by mammogram, ultrasound, MRI or biopsy.

Risk Factors

Although mucinous carcinoma can be diagnosed at any age, it tends to affect women after they’ve gone through menopause. Some studies have found that the average age at diagnosis is in the 60s or early 70s.

Inflammatory breast cancer is a rare and very aggressive disease in which cancer cells block lymph vessels in the skin of the breast. This type of breast cancer is called “inflammatory” because the breast often looks swollen and red, or inflamed.

Inflammatory breast cancer is rare, accounting for 1 to 5 percent of all breast cancers diagnosed in the United States. Most inflammatory breast cancers are invasive ductal carcinomas, which means they developed from cells that line the milk ducts of the breast and then spread beyond the ducts.

Inflammatory breast cancer progresses rapidly, often in a matter of weeks or months. At diagnosis, inflammatory breast cancer is either stage III or IV, depending on whether cancer cells have spread only to nearby lymph nodes or to other tissues as well.

Symptoms

Symptoms of inflammatory breast cancer include swelling (edema) and redness (erythema) that affect a third or more of the breast. The skin of the breast may also appear pink, reddish purple or bruised. In addition, the skin may have ridges or appear pitted, like the skin of an orange (called peau d'orange). These symptoms are caused by the buildup of fluid (lymph) in the skin of the breast. This fluid buildup occurs because cancer cells have blocked lymph vessels in the skin, preventing the normal flow of lymph through the tissue. Sometimes, the breast may contain a solid tumor that can be felt during a physical exam, but more often, a tumor cannot be felt.

Other symptoms of inflammatory breast cancer include a rapid increase in breast size; sensations of heaviness, burning, or tenderness in the breast; or a nipple that is inverted (facing inward). Swollen lymph nodes may also be present under the arm, near the collarbone, or both.

It is important to note that these symptoms may also be signs of other diseases or conditions, such as an infection, injury or another type of breast cancer that is locally advanced. For this reason, women with inflammatory breast cancer often have a delayed diagnosis of their disease.

Risk Factors

Compared with other types of breast cancer, inflammatory breast cancer tends to be diagnosed at younger ages. It is also more common and diagnosed at younger ages in African American women than in white women, and the risk increases if women are obese.

Like other types of breast cancer, inflammatory breast cancer can occur in men, but usually at an older age than in women.

Medullary carcinoma of the breast is a rare subtype of invasive ductal carcinoma (cancer that begins in the milk duct and spreads beyond it), accounting for about 3-5% of all cases of breast cancer. It is called “medullary” carcinoma because the tumor is a soft, fleshy mass that resembles a part of the brain called the medulla.

Medullary carcinoma cells are usually high-grade in their appearance and low-grade in their behavior. In other words, they look like aggressive, highly abnormal cancer cells, but they don’t act like them. Medullary carcinoma doesn’t grow quickly and usually doesn’t spread outside the breast to the lymph nodes. For this reason, it’s typically easier to treat than other types of breast cancer.

Symptoms

Like other types of breast cancer, medullary carcinoma may not cause any symptoms at first. Over time, a lump can form, and it may be soft and fleshy or somewhat firm to the touch. Most medullary carcinomas are small — less than 2 centimeters in size. Medullary carcinoma also may cause pain, swelling, redness, or tenderness in the breast.

Risk Factors

Medullary carcinoma can occur at any age, but it usually affects women in their late 40s and early 50s. Medullary carcinoma is more common in women who have a BRCA1 mutation. Studies have shown that medullary carcinoma is also more common in Japan than in the United States.