Abstract
BACKGROUND: Dermatomyositis is associated with malignant tumors including breast cancer, and inflammatory breast cancer is considered to have a poorer prognosis than most breast cancers. CASE PRESENTATION: A 74-year-old Asian woman, developed erythema on her face, back, and the back of her hands, 3 weeks before attending our department. At the same time, she had noticed a right breast mass and redness of the skin of the breast. The clinical findings and vacuum aspiration biopsy diagnosed inflammatory breast cancer and neoadjuvant chemotherapy was performed. The mass and enlarged axillary lymph nodes had shrunk, therefore a total mastectomy was performed. The sentinel lymph node biopsy was negative. She was discharged 7 days after surgery without any complications. She has received a postoperative aromatase inhibitor and is alive without recurrence. The dermatomyositis also began to improve with the start of her chemotherapy and has not recurred since the surgery. CONCLUSIONS: Neoadjuvant chemotherapy was performed for inflammatory breast cancer with dermatomyositis, and tumor shrinkage was confirmed. A total mastectomy without axillary lymph node dissection was performed. Dermatomyositis and breast cancer have not recurred. Dermatomyositis may have been a paraneoplastic syndrome due to breast cancer.