Paraneoplastic Dermatomyositis as a Potential Precursor to Thymic Carcinoma

A red rash developed on both hands of a 54-year-old man. At age 56, he was admitted to our hospital because of an abnormal shadow detected by chest roentgenogram. A detailed examination revealed an anterior mediastinal tumor and dermatomyositis. Thymectomy was performed, and pathologic examination revealed thymic carcinoma. After the surgery, the dermatomyositis symptoms improved. Although dermatomyositis associated with thymic carcinoma is extremely rare, we should account for the possibility of thymic carcinoma-associated dermatomyositis. This will allow for early identification and treatment of malignant tumors, and symptom severity may reflect the degree disease control.