synchronous idiopathic granulomatosis mastitis and breast cancer: a case report and review of literature

background: idiopathic granulomatous mastitis (igm) is a rare benign breast disease, which can mimic breast cancer. as the managements of igm and breast cancer are entirely different and the initial clinical manifestations are similar in several cases, it is very important to differentiate them. case presentation: we reported a 48-year-old female patient with igm and breast cancer. she was referred to the outpatient clinic with bilateral large masses and clinical impression of bilateral breast cancer with inflammatory features in the right side. through pathology, the diagnoses of invasive ductal carcinoma (idc) for the left breast lesion and igm for the right breast lesion were confirmed, respectively. incisional biopsy was performed for the right breast lesion to rule out breast cancer and to make sure of the diagnosis of igm. conclusion: to the best of our knowledge, breast cancer and igm were reported only in two studies. although igm is not the underlying cause of breast malignancy, the diagnosis of breast cancer should always be kept in mind. any other lesions in these patients should be assessed well to rule out breast cancer.