Maria Castillo Lara, Antonia Martínez Herrera, Rafael Torrejón Cardoso, Daniel Maria Lubián López

Granular cell tumor (GCT) is a rare neoplasm of the soft tissues, and <1% of all GCTs are malignant. It usually appears in the tongue and sometimes may affect the female breast. Initially, GCT was considered to be a myogenic lesion affecting female breast (myoblastoma). Actually, it is assumed as a tumor originating from perineural or putative Schwann cells of peripheral nerves or their precursors that grows in the lobular breast tissue, due to the immunohistochemical features. Here, we review the importance of differentiating between this tumor and malignant breast carcinoma. Mammographically, by ultrasound scan and clinically, this case appears to be a malignant tumor of the breast, but with a correct and precise diagnosis including histopathologic examination and immunohistochemical studies, it was correctly identified as a GCT. We present a case of a 52-year-old premenopausal woman. This report is of interest because of patient's familial oncologic history and personal history of gynecologic cancer. This rare tumor of the breast and the special way to approach the tumor by local anesthesia makes it interesting to communicate. This is a case of interest because GCT located in the breast is very unusual and knowledge of GCT is required for the differential diagnosis with breast cancer.