Dermatomyositis. Disease associations and an evaluation of screening investigations for malignancy.

Fifty-three adult patients (19 men, 34 women) with dermatomyositis were studied. Two had dermatomyositis associated with benign disorders. Twenty-three (43%) had a malignancy; the risk of malignancy increased with age, but there was no sex difference. Seven malignancies were recurrences and 9 were diagnosed during investigation of dermatomyositis; these 16 were suspected clinically or from abnormal results of simple investigations. Extensive screening tests did not increase the number of malignancies diagnosed. In 7 patients, a diagnosis of malignancy was made more than 9 months after onset of dermatomyositis, although a relationship between malignancy and dermatomyositis was uncertain in two cases; the diagnosis of gynecological malignancy was missed in 2 patients despite appropriate investigations, 1 patient had poorly controlled dermatomyositis, and in 2 patients late diagnosis of malignancy was due to failure to reinvestigate relapse of previously stable dermatomyositis.