A lump in the treated breast or scar: what it usually is

Most lumps that appear in a treated breast, a lumpectomy scar or a mastectomy scar are not cancer. Surgery and radiation change the tissues in ways that often create firm areas, and these are far more common than recurrence. The usual causes include scar tissue, which forms as the body heals and can feel hard or ridged; fat necrosis, where fatty breast tissue damaged by surgery or radiation becomes a firm, sometimes tender lump; a seroma or old fluid collection that has thickened; a stitch granuloma, a small reaction around a buried stitch; and oil cysts. After reconstruction, lumps can also come from fat grafting, implant folds or a flap's edge. Even so, a new lump in the treated area always deserves to be checked, because a small share of them are local recurrence, and finding a recurrence early gives the best chance of treating it successfully. It is especially important to report a lump that is new rather than one you have felt since surgery, one that is growing, a hard lump fixed to the skin or chest wall, a red or scaly rash on the scar, or small raised nodules in the skin. Your doctor will examine you and usually arrange an ultrasound, a mammogram if breast tissue remains, and often a needle biopsy for a clear answer.

Healing tissue often feels lumpy

Scar tissue and fat necrosis are the most common causes of lumps after treatment.

New or growing lumps need checking

A small share are recurrence, and early checks lead to simpler treatment.

A biopsy usually gives the answer

Imaging alone cannot always tell scar tissue from cancer.

Finding a lump after breast cancer can bring back all the fear of the first diagnosis. Here is a balanced view.

Scans can be hard to read after treatment

Scar tissue and fat necrosis can look very like cancer on a mammogram or ultrasound, so a biopsy is often needed.

Waiting for results is stressful

Ask how long the report will take and who will call you, so you are not left wondering.

Most results are reassuring

The majority of these lumps prove harmless, though every new one is worth checking.

What this page cannot tell you

It cannot say what your lump is. Only an examination and tests can.

Reconstruction adds its own possible causes of lumps, most of them harmless.

Implant folds and edges

A ripple or edge of an implant can feel like a firm ridge, especially in slim women.

Fat grafting lumps

Transferred fat does not always survive and can form small firm lumps or oil cysts.

Flap edges

The border between your own tissue and a flap may feel firm, and fat necrosis in a flap is common.

Capsular contracture

Hardening of the scar capsule around an implant can make the whole breast feel firm.