Signs and symptoms of inflammatory breast cancer include:

• Rapid change in the appearance of one breast, over the course of several weeks
• Thickness, heaviness or visible enlargement of one breast
• Discoloration, giving the breast a red, purple, pink or bruised appearance
• Unusual warmth of the affected breast
• Dimpling or ridges on the skin of the affected breast, similar to an orange peel
• Tenderness, pain or aching
• Enlarged lymph nodes under the arm, above the collarbone or below the collarbone
• Flattening or turning inward of the nipple

Inflammatory breast cancer doesn't commonly form a lump, as occurs with other forms of breast cancer.

It's not clear what causes inflammatory breast cancer.

Doctors know that inflammatory breast cancer begins with an abnormal cell in one of the breast's ducts. Mutations within the abnormal cell's DNA instruct it to grow and divide rapidly. The accumulating abnormal cells infiltrate and clog the lymphatic vessels in the skin of your breast. The blockage in the lymphatic vessels causes red, swollen and dimpled skin — a classic sign of inflammatory breast cancer.

Factors that increase the risk of inflammatory breast cancer include:

• Being a woman. Women are more likely to be diagnosed with inflammatory breast cancer than are men — but men can develop inflammatory breast cancer, too.
• Being black. Black women have a higher risk of inflammatory breast cancer than do white women.
• Being obese. People who are obese have a greater risk of inflammatory breast cancer compared with those of normal weight.