Granulomatous mastitis (GM) is a quite rare inflammatory condition of the breast with varying clinical presentations and microbiological findings. Having excluded specific diseases connected with GM, a group of idiopathic GM (IGM) remains including a special form presenting with multiple small cysts named cystic neutrophil GM (CNGM). The aetiology is unknown, and clinical investigation methods as well as treatment options are controversial. The purpose of this review is to describe diagnostic considerations and controversies in the treatment of IGM and CNGM.