Breast Cancer in a Pectoralis Major Myocutaneous Flap Used for the Reconstruction of Tongue Cancer: A Case Report.

Breast cancers are the most common cancers in women. However, breast cancer occurring in a pectoralis major myocutaneous flap is extremely rare. This article describes a case of breast cancer occurring in such a flap used for reconstruction of the tongue in a 72-year-old woman. Follow-up computed tomogram depicted a slowly growing mass in the flap. Thirty-nine months postoperatively, a fine-needle aspiration biopsy specimen taken from the lesion suggested glandular carcinoma. The patient was diagnosed with breast cancer in the neck area of the flap and tumor excision was performed. Histologic examination of the excised tumor showed tumor cells arranged in cords, with tubular and cribriform carcinomas near the pectoral muscle with adipose tissue. The cytoplasm was abundant and eosinophilic. Thus, the patient was diagnosed with invasive ductal carcinoma in the pectoralis major flap. Sequential radiotherapy was performed to the neck with a total radiation dose of 50 Gy. Furthermore, the patient received oral anastrozole 1 mg daily as systemic adjuvant therapy for the receptor-positive breast malignancy. One year after surgery, the patient was alive with no evidence of disease. Including this case, only 2 cases of breast cancer in a pectoralis major myocutaneous flap used for reconstruction in the head and neck region have been reported.