Lymph node metastasis within the pectoralis major muscle in breast cancer--a case report.

We report herein, a case of a 75 year old woman with breast cancer in whom lymph node metastasis within the pectoralis major muscle was found. The breast mass measured 10 X 6 cm, and its overlying skin was red and edematous, suggesting inflammatory carcinoma. An extended radical mastectomy was performed and the lesion was histologically confirmed to be solid-tubular carcinoma with regional lymph node involvement. In the pectoralis major muscle, where lymph nodes do not usually exist, one positive metastatic lymph node and another metastatic lymph node-like nodule were histopathologically confirmed. To our knowledge, no other such case has ever been reported, yet the possibility of lymph nodes existing in the pectoralis major muscle, albeit rare, should nevertheless be considered in the treatment of breast cancer.