Rare diagnosis of locally advanced triple‑negative breast cancer with paraneoplastic dermatomyositis: A case report and literature review

Paraneoplastic dermatomyositis (DM) is a rare autoimmune condition that primarily affects the skin and muscles; it is associated with various malignancies, including breast cancer. The present case report investigates the clinical presentation, therapeutic considerations and relevant literature regarding DM in the context of locally advanced triple-negative breast cancer (TNBC). A 43-year-old female patient presented with progressive myalgia, dysphagia and characteristic skin rashes. Subsequent investigations confirmed locally advanced TNBC and concomitant DM. Due to the severely weakened state of the patient, the standard treatment of neoadjuvant chemotherapy was contraindicated. The patient initially received corticosteroid therapy, which led to partial symptom improvement, followed by a modified radical mastectomy and adjuvant chemotherapy. Following surgical intervention, the patient experienced significant alleviation of DM symptoms. The present study underscores the critical role of early malignancy identification and intervention in managing DM associated with breast cancer; in addition, it explores the epidemiology, risk factors, pathogenesis, diagnostic modalities and treatment strategies for breast cancer-associated DM. The potential challenges in treatment selection are highlighted, particularly in patients with severe presentations. Mastectomy can emerge as a viable therapeutic option to achieve symptom control and facilitate subsequent oncological management.