Oligometastatic Breast Cancer With Cutaneous Involvement and Paraneoplastic Hypercalcemia in a Young Woman.

Cutaneous involvement in breast cancer is typically associated with locally advanced or neglected disease. In young women, such presentations are often associated with a more aggressive biological behavior. We report the case of a woman in her early 40s presenting with a large, cutaneous-involved, hormone receptor-positive, human epidermal growth factor receptor 2 (HER2)-negative, right breast cancer with neuroendocrine differentiation. Imaging revealed axillary, supraclavicular, and right cervical lymph node involvement, with no evidence of distant metastasis. Laboratory evaluation at diagnosis demonstrated malignant hypercalcemia refractory to medical treatment. The patient received neoadjuvant chemotherapy, achieving resolution of hypercalcemia and a significant clinical and radiologic response, followed by surgery, radiotherapy, and adjuvant endocrine therapy. At 24 months post-surgery, the patient remains free of disease. This case underscores the importance of prompt multidisciplinary management in aggressive presentations of breast cancer, even when associated with paraneoplastic syndromes.