Q. My breast swelled up and was hot and painful to the touch. My doctor treated me for mastitis, but it turned out to be inflammatory breast cancer. I think other women should be aware that not all breast cancers start with a lump.

A. That’s right. Inflammatory breast cancer does look a lot like mastitis, an infection of the breast that can have many causes. Mastitis is more common when you’re breast-feeding; and some women have a lifelong proclivity to bouts of mastitis. But if you’re...