Breast Cancer Associated Dermatomyositis: Parallel Occurrence, Remission, and Relapse of the Two Diseases in a Patient: A Case Report

Abstract

Dermatomyositis (DM) is an uncommon inflammatory disease with characteristic cutaneous findings associated with muscle weakness. Although the majority of cases of DM is idiopathic, an increased incidence of underlying malignancy in patients with dermatomyositis has been reported. An underlying breast cancer is found in nearly 10% of cases of malignancy-associated DM. We report a case of a 50-year-old nulliparous woman who was diagnosed with dermatomyositis according to Bohan & Peter criteria. After performing a cancer screening which was negative, the patient was treated with topical and oral corticosteroids; then she was put under immunosuppressors with minimal improvement. One year later, a right breast mass was detected at systemic clinical examination prompting diagnostic workup of breast cancer. After mammogram which showed a suspicious mass, the patient underwent stereotactic breast biopsy which revealed an invasive ductal carcinoma. Computed Tomography (CT) scan of the chest, abdomen, and pelvis and bone scan revealed no distant metastases. The patient underwent mastectomy and axillary dissection followed by adjuvant chemotherapy, radiotherapy, and adjuvant tamoxifen. Simultaneously, she continued the treatment for her Dermatomyositis. Her cutaneous and musculoskeletal symptoms improved dramatically following the treatment of her breast cancer. After four years of uneventful follow-up, the patient reported the recurrence of symptoms suggestive of dermatomyositis. A thoracic-abdominal-pelvic CT scan has been performed and revealed distant metastases. Therefore, our case demonstrates the parallel evolution between dermatomyositis and breast cancer after surgery, local radiotherapy and systemic therapy.