Granulomatous mastitis is a benign but rare inflammatory condition. It usually presents as a breast lump, often tender in the early stages. Sometimes this affects the overlying skin.
Mammography can sometimes be misleading and falsely interpreted as a cancer. Similar false investigations may be drawn from ultrasound investigations. A needle biopsy is usually helpful in showing inflammatory cells.
A definite diagnosis, however, is often made after a surgical biopsy. Under the microscope, there are typical abnormal cells reminiscent of chronic inflammation.
Granulomatous mastitis does not predispose to developing breast cancer.
The majority of granulomatous mastitis occurs with no known predisposing factor.
A variety of bacterial, fungal and parasitic infections can sometimes result in granulomatous mastitis.
These are all rare and within this group, tuberculosis is probably the commonest identified bacterial organism.
There are other non-specific rare inflammatory and auto-immune causes such as sarcoidosis and granulomatosis.
Granulomatous changes can also be seen as a result of a foreign body reaction. Silicone granulomas which may be related to previous breast implants would fall into this category.
The diagnosis and investigation of granulomatous mastitis is as for any breast lump, with clinical examination, mammography, ultrasound and needle biopsy.
Often a definitive diagnosis is made at excision biopsy. There is a risk that the surgical excision biopsy wound may heal slowly because of the underlying inflammatory change.
It is important that a breast cancer is excluded, as the clinical and radiological features of granulomatous mastitis can mimic breast cancer.
Sometimes, a course of steroid treatment is necessary to enable the lesions to stop developing and for healing. Other anti-inflammatory drugs are also sometimes used.
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