Idiopathic granulomatous mastitis (IGM) is a rare benign disease of uncertain etiology having diagnostic and therapeutic challenges which was treated surgically with poor outcome. This study tried to clarify the diagnostic difficulties and to evaluate different lines of treatment and their outcomes. This is a prospective describtive study included 9 patients with proven IGM based on clinical, radiological and pathological examinations. The outcome of diffferent treatment options was evaluated after a mean follow-up period of 18.9±2.1 months. All patients presented with a history of a unilateral painful palpable breast lump. Patients had a clinical presentation mimic inflammation in (56%) and malignancy in (44%). Histopathology was conclusive in exclusion of other causes of granulomas thus diagnosing IGM while ultrasonography and mammography was not. Eight patients out of nine responded to corticosteroid therapy (mean 3.5 months) while one was resistant and responded to surgical excision. At follow-up (22%) had recurrence and responded well to a second course of corticosteroid. A combination of surgery and medical treatment for Idiopathic granulomatous mastitis according to the severity is better than any alone. Keywords: Granulomatous lobular mastitis, corticosteroid treatment, Breast Carcinoma.