Axillary Accessory Breast Cancer Performed Reconstruction Using a Local Flap: A Case Report

Accessory breast cancer is rare, with approximately two-thirds of cases arising in the axillary region. Wide local excision is commonly performed; however, large axillary defects can lead to postoperative scar contractures and limited range of motion in the ipsilateral upper limb.

A 67-year-old woman presented with a palpable mass and erythema in the left axilla. Physical examination revealed a 2-cm indurated lesion with erythema in the left axilla. Ultrasonography revealed an irregular 14-mm hypoechoic mass with suspected dermal invasion. Skin punch biopsy suggested the presence of invasive carcinoma in the dermis, suggestive of invasive lobular carcinoma on immunohistochemistry. Contrast-enhanced breast MRI revealed no abnormal breast enhancement. Systemic evaluation revealed no evidence of distant metastases. The patient underwent a wide local excision of the left axillary lesion with axillary lymph node dissection, followed by local skin flap reconstruction of the axillary defect. Histopathological examination revealed an invasive lobular carcinoma of pleomorphic type (pT1cN1aM0, pStage IIA, triple-negative subtype), associated with heterotopic breast tissue and lobular carcinoma in situ. Postoperative adjuvant chemotherapy was administered. The patient experienced no limitations in left upper limb range of motion and survived without recurrence.

During the surgical treatment of axillary accessory breast cancer, reconstructive procedures should be considered based on the size of the skin defect to prevent postoperative scar contracture.