Why does HER2-positive breast cancer cause a breast lump?

Breast Lump is a very common presentation of HER2-Positive Breast Cancer because rapidly multiplying abnormal cells can form a concentrated area of breast tissue. As the cells and surrounding tissue increase, the area may feel firmer or different from the breast around it.

HER2-positive breast cancer has cancer cells with higher amounts of a growth-promoting protein called HER2. Signals through this protein can encourage cells to multiply. A cluster of abnormal cells may therefore create a palpable mass, while nearby inflammation or changes in supporting tissue can add to firmness.

A breast lump has many possible causes, including cysts, fibroadenomas, infection, and normal hormonal changes. Feeling a lump cannot establish its type or HER2 status. Assessment may include a clinical examination, imaging such as ultrasound or mammography, and a needle biopsy when indicated. Laboratory testing of sampled tissue can identify HER2 status.

Arrange an appointment for any new, persistent, enlarging, or unusual breast lump. Note when you first felt it, whether it changes with your menstrual cycle, and whether there are skin or nipple changes. Do not repeatedly press the area, as this can make it sore. If cancer is diagnosed, your care team can explain how tissue findings guide treatment choices.

Seek prompt medical review for a lump with skin dimpling, redness, warmth, nipple inversion, bloody discharge, an ulcer, or a new lump in the armpit. Urgent care is appropriate for fever with a painful, red breast or rapidly worsening swelling. These changes can have different causes, but they should be examined rather than watched indefinitely.

Ask: Which imaging test is suitable for me? Do I need a biopsy? What did the tissue test show, including hormone receptors and HER2? If the result is cancer, what treatments are available and who will coordinate my care?