Suspected cup syndrome. Diagnostic imaging of a misunderstood breast tumor for its uncommon location.

The case of a 41-year-old female patient with axillary lymphadenopathies and negative clinical and mammographic examinations is discussed. In the suspicion of a cup syndrome of breast origin, breast sonography was performed. While the absence of alterations was confirmed, a right parasternal swelling was highly suggestive of malignancy. On histology, a malignant parasternal nodule was diagnosed. Breast MRI was performed and an ipsilateral malignant focal lesion was visualized. Chemotherapy was administered but after a disease-free interval leptomeningeal and cerebral metastases appeared.