BackgroundIdiopathic granulomatous mastitis (IGM) is a benign rare inflammatory disease of the breast. Due to its uncommon etiology, diagnosis and treatment is still unknown. Selection of a standard method for diagnosing idiopathic granulomatous mastitis is sophisticated. In view of non-definitive clinical and imaging finding, histopathology is the cornerstone of definitive diagnosis.ObjectiveTo determine and help solve the dilemma of treatment and diagnosis of idiopathic granulomatous mastitis.MethodsThis historical cohort study was conducted on 48 patients who referred to the general surgery clinic of Imam Khomeini Hospital of Urmia, were diagnosed with IGM and were histopathologically selected by census using the registry system, in Urmia city, Iran, during 2010–2015 so that medical reports, ultrasonography (US) and mammography (MMG) findings, follow-up information and recurrence rate were obtained from records. The data were analyzed using SPSS software version 18 and descriptive statistics were used.ResultsAccording to records, 68.75% of patients (n=33) had palpable mass, 45.83% of patients (n=22) had breast pain and swelling, erythema and 20.83% of patients (n=10) had purulent drainage. Of the 48 patients 12 (25%) had mammography, which revealed the following findings: mass with irregular border in 6 patients, skin thickness in 2 cases (4.16%), and parenchymal asymmetry in 4 cases (8.33%). Minimum follow-up was 24 (range 24–56) months.ConclusionsAccording to our findings, histopathology of the disease is fundamental for correct diagnosis. Steroid therapy as a therapeutic method such as prednisolone was an effective and applicable choice in the treatment of idiopathic granulomatous mastitis by decreasing in inflammation.