Dermatomyositis and malignancy: a retrospective study of 115 cases

Aim of this study was to identify the association between dermatomyositis and malignancy in China. Methods: We retrospectively analyzed the clinical data of 115 cases of dermatomyositis associated with malignancy. Results: From 1974 to 2008, there were 678 cases of dermatomyositis collected from the Second Affiliated Hospital, Sun Yat-Sen University, China. Among them, 115 cases (17.0%) were associated with malignancy. 7.4% (22/297) of patients under 40 years old were diagnosed with malignant tumor, while 24.4% (93/381) of patients aged 40 years or above were associated with malignancy. Malignancy preceded dermatomyositis in 14 cases. Dermatomyositis and malignancy were diagnosed at the same time in 22 patients. Another 79 patients were found to have cancer within 3 years after the dermatomyositis was diagnosed. Among them, cancer was detected in 66 patients in the first year, 11 patients in the second year and only 2 patients in the third year. Nasopharyngeal cancer made up 51.3% (59/115) of the associated malignancies, while lung cancer accounted for 17.4% (20/115). Other malignancies associated with dermatomyositis included liver cancer, ovarian cancer, cervical lymph node metastases of unknown origin, cholangial cancer, esophageal cancer, colon cancer, laryngeal cancer, renal cancer, tongue cancer and lymphoma. Conclusions. Dermatomyositis associated with malignancy was more common in patients aged 40 years or above. Malignancy was often detected within the first year after the onset of dermatomyositis. The most common malignancy associated with dermatomyositis was nasopharyngeal cancer, followed by lung cancer in Guangdong, China.