There's Usually No Lump in This Rare, Aggressive Form of Breast Cancer. Here's What You Need to Know

Inflammatory breast cancer (IBC) is a rare, aggressive form of breast cancer that tends to develop quickly, sometimes in just a few weeks or months. IBC starts in the milk ducts of the breasts and, by the time it has been diagnosed, has usually already spread to the lymph nodes and further.

The distinctive symptoms of redness, swelling, and tenderness are “because cancer cells block the lymphatic vessels in the skin overlying the breast,” says Jessica Maxwell, MD, assistant professor of surgical oncology at the University of Nebraska Medical Center.

The lymph vessels carry lymph fluid, part of the body’s infection-fighting system, throughout the body.

Although IBC accounts for only about 1% to 5% of all breast cancers, it has a steeper mortality rate than other malignancies in the breast.

The symptoms of IBC are often mistaken for an infection. Redness and swellingtypically cover at least a third of the breast, which may also be warm to the touch.

The most characteristic symptom of IBC is ridged, pitted, or dimpled skin caused by the buildup of lymphatic fluid in the skin. This is called “peau d’orange” or “skin of an orange.”

“The skin gets very swollen and thick and the pores get larger,” explains Lauren S. Cassell, MD, chief of breast surgery at Lenox Hill Hospital in New York City.

Sometimes the nipple may be flattened or inverted, the skin may look red, purple, or bruised, and lymph nodes under the arm or near the collarbone may be swollen. Some women also have a feeling of heaviness or burning in their breasts. Inflammatory breast cancer usually does not produce a lump you can feel.

Inflammatory breast cancer causes

No one knows exactly what causes IBC other than it usually starts in the milk ducts of the breast.

“We know it generally begins like other cancers where you have an abnormal cell within the breast and typically a mutation within that cell’s DNA instructs the cell to grow or divide very rapidly,” says Dr. Maxwell.

IBC differs from other cancers in that “rapidly dividing cells accumulate and clog those lymphatic vessels and skin,” she adds.

Inflammatory breast cancer diagnosis

IBC is easily confused with a breast infection, especially in younger women who may be breastfeeding. In fact, it’s often first treated with antibiotics, says Dr. Cassell. “If you have a patient who does not respond to antibiotics in seven to 10 days, then you have to have a very strong consideration for IBC.”

If that’s the case, the next step is usually a biopsy, she adds. “You don’t wait six months trying to treat this with antibiotics.”

A mammogram doesn’t usually detect IBC, but it can help with diagnosis. “We still usually get imaging to look at the breast tissue itself to see if there’s any kind of underlying abnormality,” says Dr. Maxwell. “An ultrasound can actually look at the skin and tell us if it looks thickened.” MRIs may also be helpful in diagnosing IBC.

Ultimately, though, a diagnosis can only be made with a biopsy, which is taking a sample of tissue and studying it under a microscope. Then you may need other tests like bone scans or chest X-rays to see if and where the cancer has spread.

Inflammatory breast cancer risk factors

The biggest risk factor for inflammatory breast cancer is being a woman, although men can get it as well.

Black women are at an even higher risk than white women. People who are obese have a greater chance of developing IBC than those at a normal weight.

IBC tends to occur in younger women, with the average age at diagnosis being 52, versus 57 for other types of breast cancer.