Breast cancer and dermatomyositis: a case study and literature review

A 49-year-old woman presents with an extensive violaceous rash, rapidly progressive proximal muscle weakness, and dysphagia to solids, consistent with a diagnosis of dermatomyositis. Two weeks later, she palpates a mass in her left breast and is diagnosed with her2-positive metastatic invasive ductal carcinoma of the breast. There is a well-established association between dermatomyositis and malignancy. However, the specific association between breast cancer and dermatomyositis has not been well characterized. No guideline for oncologists managing these patients has been established. Recently, 3 cases of breast cancer and dermatomyositis were diagnosed at our institution. A review of the literature was pursued to characterize the association between breast cancer and dermatomyositis. A review of 178 papers identified 22 cases of breast cancer with dermatomyositis. Most patients (71%) presented with stage iii or iv breast cancer. The median time between the diagnosis of breast cancer and the onset of dermatomyositis symptoms was 1 month. Three quarters of the patients were steroid-responsive and able to taper. Half the women with follow-up data experienced a documented cancer relapse associated with a new flare of cutaneous symptoms. The presence of dermatomyositis appears to be associated with more-advanced breast cancer stage and is most commonly associated with invasive ductal carcinoma. In our review, treatment of cancer alone is insufficient to adequately control the cutaneous and myopathic manifestations of dermatomyositis, which can significantly affect quality of life. A multidisciplinary approach, including close collaboration with rheumatologists and dermatologists, is therefore important in the diagnosis and management of oncology patients with dermatomyositis.