Causes of granulomatous mastitis

In idiopathic granulomatous mastitis, the immune system appears to drive inflammation around milk-producing lobules after other causes have been excluded. It is not caused by poor hygiene.

The term describes a particular pattern of inflammation seen in breast tissue rather than one universal trigger. Some cases follow changes associated with pregnancy or breastfeeding, and milk leakage within the breast may contribute to inflammation. Certain bacterial, fungal or mycobacterial infections can cause a granulomatous pattern and need different treatment.

Granulomatous mastitis can present with a painful firm area, redness, swelling, an abscess, skin breakdown or nipple discharge. These findings can resemble ordinary mastitis and, sometimes, breast cancer. Symptoms alone cannot identify the cause, so clinicians may use imaging, fluid or tissue samples, cultures and a biopsy to reach a diagnosis.

Arrange a breast assessment for a new lump, persistent breast inflammation or symptoms that have not improved with initial treatment. Do not squeeze or repeatedly drain an affected area yourself. If you are breastfeeding, continue or adjust feeding only with advice suited to your pain, milk supply and medicines. Management may involve observation, drainage, antimicrobial treatment when an infection is identified, or medicines that reduce inflammation after infection has been considered.

Get prompt medical help if breast redness is spreading, pain or swelling is rapidly worsening, pus is draining, or you feel feverish, faint, confused or very unwell. A new breast lump, skin dimpling, nipple pulling inward, bloody discharge or symptoms that persist after treatment also require timely clinical assessment. These features need evaluation because several breast conditions can look alike, not because they establish a particular diagnosis.

Ask what tests will distinguish idiopathic inflammation from infection, whether a sample will be sent for culture, and whether imaging or biopsy is recommended. Discuss how treatment could affect breastfeeding, which changes should trigger an earlier review, how wounds should be dressed and how progress will be monitored.