Granular cell tumor of the breast.

We report a case of a 43-yr-old woman with a granular cell tumor of the breast. She presented with a palpable mass of the left breast of 2-yr duration. On physical examination, a firm, painless, well-defined mass located at the union of the upper quadrants was observed and a palpable homolateral axillary lymph node. The tumor was dense with ill-defined borders at mammography and hypoechoic, hypovascular, and poorly limited at ultrasonography. Fine needle aspiration cytology of the lesion was performed. Cytologic examination revealed the presence of highly cellular material, composed of both large cohesive groups and single cells often admixed with connective tissue. These cells had ill-defined abundant granular cytoplasm and bland regular small nuclei. Nucleoli were inconspicuous. Neither mitoses nor necrosis were noted. The cytological diagnosis of granular cell tumor of the breast was confirmed by histological examination of the surgical specimen following a breast lumpectomy.