Abstract
Background. Dermatomyositis is known to be associated with malignancy. However, cases of dermatomyositis occurring after a diagnosis of lung cancer are rare. Case. A 60-year-old male underwent left upper lobectomy for adenosquamous lung carcinoma (T2aN1M0 p-stage IIA) in 2006. The patient relapsed in 2008 and presented with mediastinal lymph node metastasis; therefore, he underwent treatment with chemoradiotherapy. He was admitted to our hospital in 2011 due to a rash on his neck and an abnormally high creatine kinase level. The patient was diagnosed with dermatomyositis based on a positive Gottron's sign and weakness of the muscles and extremities. Paraneoplastic syndrome was suspected, as the chest computed tomography revealed mediastinal lymph node metastasis. He underwent radiotherapy; however, the muscle weakness progressed. His symptoms improved following treatment with betamethasone and cyclophosphamide for dermatomyositis and gefitinib for lung cancer harboring an epidermal growth factor receptor mutation. Eight months later, multiple pulmonary metastases and recurrence of dermatomyositis were observed, and the patient received chemotherapy and steroid therapy. He was diagnosed with paraneoplastic syndrome based on the presence of an elevated creatine kinase level and the deterioration of dermatomyositis at the time of tumor relapse. Conclusions. We encountered a rare case of dermatomyositis as a paraneoplastic syndrome following the diagnosis of lung cancer.
