Dermatomyositis and malignancy: a retrospective study of 115 cases.

Aim of this study was to iden- tify the association between dermatomyositis and malignancy in China. Methods: We retrospectively analyzed the clinical data of 115 cases of dermatomyositis as- sociated with malignancy. Results: From 1974 to 2008, there were 678 cas- es 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 tu- mor, while 24.4% (93/381) of patients aged 40 years or above were associated with malignancy. Malignancy preceded dermatomyositis in 14 cas- es. Dermatomyositis and malignancy were diag- nosed 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 can- cer made up 51.3% (59/115) of the associated ma- lignancies, while lung cancer accounted for 17.4% (20/115). Other malignancies associated with der- matomyositis included liver cancer, ovarian can- cer, 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 dermato- myositis. The most common malignancy associat- ed with dermatomyositis was nasopharyngeal can- cer, followed by lung cancer in Guangdong, China.