We present the clinical, light microspcpic, and immunohistochemical features of two new cases of leiomiosarcoma of the female breast. both the patients were old (83 and 86 years) and were referred with history of long-standing breast lump. The results of the physical examination and the preoperative radiologic investigation suggested a phyllodes tumor. The patients were treated with mastectomy. The tumors measured 6 an 6.5 cm in the largest dimension, respectivelly, and were composedof fascicles of atypical, actively proliferating spindle cells, oftren intesecting hte right angles. The axillary lymph nodes wre free of tumor. Immunohistochemically, the tumor cells were positive for desmin, muscle-specific actin, and vimentin and negative fo othe markers, including keratins and hormone receptors. Focal rabdomyoblastic differentaitation was noted in one case. Follow-up at 1 year is negative for metastases or local recurrence. Our study confirms that leiomyosarcoma of the breast is a locally invasive neoplasmand that it could represent a peculiar anatomic entity among mesenchymal tumors of the breast.
