Abstract: Objective  To investigate the clinical features and related factors of polymyositis(PM) and dermatomyositis(DM) combined with malignancy in order to make the early diagnosis and intervene the disease,  and  improve survival rate of PM/DM patients. Methods  The  data of 117 PM/DM patients admitted to the hospital in the past 4 years were collected and compared.Results  ①PM/DM patients with malignant tumors (14 cases) were older than those with PM/DM without malignant tumors (103 cases) (t=2.493, P<0.05)（t=2.493，P<0.05).  There was no significant difference in the incidence, sex and duration of PM and DM malignant tumors between the two groups; ②The incident of model skin rash such as Heliotrop rash,  Vshaped rash in the neck and chest area and Gottron sign in malignancy group were all higher than that of nonmalignancy group(P<0.01)，and the incidence of arthritis was lower than nonmalignancy group(P<0.05)； ③The elevated ESR in malignancy group was higher than nonmalignancy group(Z=-2.809，P<0.01)，but  GLOB was lower than that of nonmalignancy group(Z=-2.9149，P<0.01). Conclusion  PM/DM is easy to be associated with malignancy,  which is common in elderly  patients with the model skin rash,  elevated ESR,  lower GLOB and without arthritis.Therefore,  PM/DM patients who present the above symptoms and serologic results should be screened for malignant tumors closely.

Key words: dermatomyositis, neoplasms, second primary, sings and symptoms