What should you know about a black lump under the breast?

A dark spot or bump in the fold beneath the breast may be a blocked pore, an inflamed hair follicle, or a cyst close to the skin. Sweat, friction, and tight clothing can irritate this area. Dark colour can also reflect dried blood, a scab, or bruising after pressure or an unnoticed knock. A deeper lump may not be caused by the skin colour over it. Breast cancer can present as a new lump or skin change, although a black appearance does not by itself establish that diagnosis.

Notice whether the lump is tender, warm, growing, fixed in place, draining, or associated with redness, dimpling, nipple change, or a lump in the armpit. These details help a clinician decide whether the change is mainly in the skin or needs breast imaging and examination.

Do not squeeze, pierce, or repeatedly rub the lump. Keep the fold clean and dry, choose breathable clothing, and note when you first noticed it. A warm, clean compress may soothe a tender surface bump, but stop if pain or swelling increases. Arrange a clinical assessment for a new lump that does not settle, returns, or feels deeper than the skin. A clinician may inspect the skin and breast and choose an ultrasound or another test based on the findings.

Seek prompt medical care if the area becomes rapidly larger, very painful, hot, or increasingly red, or if pus, fever, or feeling unwell suggests infection. Seek urgent assessment for a new breast lump with marked skin dimpling, nipple inversion, bloody discharge, or swelling in the armpit. A black area that spreads, bleeds without being touched, or develops an open sore also needs prompt review. If you are unsure whether the change is in the skin or breast tissue, arrange an examination rather than trying to diagnose it at home.

Ask: Does this look like a skin problem or a breast-tissue lump? What changes should make me return sooner? Would an ultrasound or other assessment help? Could friction, infection, or a recent injury explain the colour?