Sarcoidosis is a systemic granulomatous disease of unknown aetiology. The breast is involved in less than 1% of cases. Breast can be either a primary or a secondary site of presentation. Breast sarcoidosis often mimics carcinomas at clinical examination. We report a case of breast sarcoidosis detected during screening mammography in a 57-year-old woman. The lesion presented as a 1.4 cm nodule located in the right breast. On histology, it was characterized by non-caseating giant cell granulomas. Differential diagnoses included idiopathic granulomatous mastitis, tuberculosis, fungal infection, cat-scratch disease and sarcoid-like reactions to cancer. Further clinical and laboratory investigations were consistent with a diagnosis of sarcoidosis. Specifically, serum levels of angiotensin-converting enzyme (ACE) were elevated and a CT scan showed small bilateral pulmonary nodules distributed along the pleura and bronchovascular bundles (perilymphatic pattern), as well as enlarged bilateral hilar and mediastinal lymph nodes. The patient received corticosteroid treatment, and is presently asymptomatic. Breast involvement by sarcoidosis, although rare, should be considered when dealing with granulomatous lesions of the breast.