RESUMO
A 54-year-old male presented with a painless, hard, irregular lump in his right breast, with fixation to the pectoralis muscle. Mammography and ultrasound showed a 2.5-cm mass suspicious of malignancy. The patient underwent a wide local excision. A 2.5-cm hard, stellate lump was found and sent to the pathologist, which revealed this to be a benign granular cell tumor. Granular cell tumor of the breast is a rare neoplasm, of unknown etiology, which is benign in 98% of cases, but mimics breast cancer, causing challenging diagnostic and therapeutic dilemmas. Traditional imaging techniques do not recognize any feature specific for this tumor. Only excisional biopsy allows the detection of the distinct histological and immunohistochemical profile of the lesion (granular cytoplasm and staining for the S-100 protein). Only local surgical excision is indicated. General and senologist surgeons must be aware of this entity to avoid unnecessary mastectomy or lymphadenectomy.