Abstract
This case focuses on breast cancer surgery in the setting of Poland syndrome (PS), a rare congenital condition characterised by unilateral absence or hypoplasia of the pectoral muscles. The literature describing breast cancer in patients with PS is limited. We present a case of an elderly woman with left-sided PS in whom breast cancer was incidentally detected during routine surveillance imaging for malignant melanoma. Imaging and biopsy confirmed a small invasive carcinoma, and the patient underwent mastectomy with sentinel lymph node biopsy. Intraoperatively, the absence of the pectoralis major and minor muscles resulted in altered anatomy, with minimal tissue separating the breast from the underlying chest wall and underlying heart. Identification of the deep layer of the superficial fascia allowed safe dissection. Histopathology showed no nodal involvement, and the postoperative course was uncomplicated. This case highlights the importance of recognising PS and adapting surgical technique to ensure safe oncological outcomes.