Idiopathic Granulomatous Mastitis (IGM)

Idiopathic Granulomatous Mastitis (IGM)

Idiopathic Granulomatous Mastitis (IGM) is a benign (non-cancerous) condition increasingly affecting women. The exact cause remains unknown. IGM causes long periods of significant inflammation of the breast and overlying skin. IGM can come back several times over years.

Who gets IGM?

IGM is common in young women (less than the age of forty), and is often seen in women of Hispanic descent. It is commonly diagnosed in women who have had at least one child and who have also breastfed.

How does IGM present?

Women may notice significant swelling, discomfort, overlying skin changes or scarring of the skin. IGM may also cause drainage of bloody or yellow fluid. Breasts affected by IGM may become cosmetically deformed. IGM may be mistaken for cancer.

What causes IGM?

It is not known if IGM is is caused by a bacterial infection. There may be a connection between IGM and pregnancy, as the breast changes that are seen during pregnancy may increase the likelihood of developing IGM. It is also thought that IGM may be triggered by a person’s own immune system in response to an allergic reaction or irritation resulting in inflammation.

How is IGM diagnosed?

Breast ultrasound (sonogram) guided core needle biopsy (needle that removes a small piece of tissue from the area) is the best way to get tissue to diagnose IGM. At times, with classic symptoms and clinical presentation of IGM, a biopsy will not be necessary for the diagnosis. Testing the tissue or fluid removed from the affected breast for the presence of infectious organisms may be helpful for treating patients with IGM.

How is IGM treated?

IGM is difficult to treat, as the exact cause remains unknown. Many treatment options are available, commonly oral and topical medications.  Topical steroids (a cream to place on your skin) may be prescribed to the affected areas. In addition, medications taken by mouth aimed at targeting and reducing the severe inflammation may be given, such as oral steroids (prednisone) or methotrexate.

Antibiotics may be given if the skin changes are concerning for an infection (cellulitis), but are not the first choice. Collections of fluid in the breast that are painful may be aspirated (fluid removed with a small needle) in the clinic for relief. IGM patients should always have a test to rule out tuberculosis (TB), as TB mimics IGM.

Patients should not become pregnant while undergoing oral medical therapy for IGM as the medications may not be safe for the fetus. Surgery to excise the affected area is reserved for severe cases that do not respond to medications, as this may result in a larger cosmetic deformity or an area that remains open on the breast for several weeks.

Regardless of the treatments, IGM takes months to resolve. It may be up to two years before the breast tissue feels “normal.” There may also be scarring that remains after the skin changes resolve. It is important to note that, regardless of treatment, IGM is a self-limiting condition that usually resolves over a few years time. IGM does not increase the risk of developing breast cancer.