Granulomatous inflammation of the breast is associated with foreign material, infectious agents, or idiopathic diseases, including autoimmune diseases. GAP of the breast is a rare, idiopathic disease, with nonnecrotic granulomas and angiitis in the subcutaneous fat tissue and breast parenchyma. It has been described only in one pathologic report. In this report, we describe mammographic and sonographic findings of a case of GAP in the breast.