Some rashes occur only on the breast. But most breast rashes have the same possible causes as rashes on other parts of the body.

Causes of a rash that occurs only on the breast include:

1. Breast abscess
2. Inflammatory breast cancer
3. Mammary duct ectasia
4. Mastitis (an infection in breast tissue)
5. Nipple dermatitis
6. Paget's disease of the breast

Causes of a rash on the breast that can also occur on any part of the body include:

1. Atopic dermatitis (eczema)
2. Candidiasis (especially under the breasts)
3. Cellulitis (a skin infection)
4. Dermatitis
5. Hives and angioedema
6. Psoriasis
7. Scabies
8. Seborrheic dermatitis
9. Shingles