Breast carcinoma occurring from chronic granulomatous mastitis

Chronic granulomatous mastitis is known as a benign and relatively rare disorder that is often difficult to differentiate from breast carcinoma. We highlight the case of a 34-year-old woman who had recurrent episodes of right breast swelling and abscess for 8 years. These were proven to be chronic granulomatous mastitis by tissue biopsies on 3 different occasions. Her condition improved on similar courses of antibiotics and high-dose prednisolone. However, she subsequently developed progressive loss of vision due to an orbital tumour. She then underwent a craniotomy and left orbital decompression with excision of the tumour, which proved to be a metastatic carcinoma. A trucut biopsy of the right breast was then done and showed features consistent with an infiltrating ductal carcinoma. This case illustrates the possibility that chronic granulomatous mastitis could be a precursor for malignancy and the difficulty in differentiating one from the other. The possible mechanisms of development and the implications for future management are also discussed.