Isolated Supraclavicular Lymph Node Metastasis in Primary Breast Carcinoma: A Multimodality Imaging Diagnosis of a Rare Pattern of Spread

Breast carcinoma commonly metastasizes to axillary and internal mammary lymph nodes, while isolated supraclavicular lymph node metastasis (ISLM) without axillary involvement is rare. We report a 70-year-old female who presented with a painless left supraclavicular swelling and an unexamined left breast mass. Imaging, including ultrasonography, contrast-enhanced CT, PET/CT and histopathological examination revealed a left breast lesion and ISLM, with no axillary or distant metastases. The patient underwent left mastectomy with sentinel lymph node biopsy, followed by adjuvant chemotherapy, radiotherapy including the supraclavicular region, and endocrine therapy. This case highlights the diagnostic challenge of ISLM, emphasizing the role of multimodal imaging and histopathologic confirmation. Early recognition and aggressive multimodality treatment can achieve locoregional control and favorable outcomes, supporting curative-intent management in selected patients with ISLM.