DM N=74 PM n=20 OS n=24 Total n=118 Malignancy 6 (8%) 3 (15%) 2 (8.3%) 11 (9.3%) Before the diagnosis of IIM 1 - - 1 After the diagnosis of IIM 5 3 2 10 Location of malignancy Cervix Endometrium Ovary Urinary Tract Cecal appendix Unknown primary Salivatory gland 1 1 1 - 1 2 - 1 - - 1 - - 1 2 - - - - - - 4 1 1 1 1 2 1 Histological variant Adenocarcinoma Epidermoid 4 2 1 2 1 1 6 5

Table 2: Malignancy characteristics in 118 patients with Dermatomyosytis (DM), Polymyositis (PM) or Overlap Syndrome (OS).