Diagnosis of dermatomyositis was definitely set according to the criteria of Bohan and Peter. Epidermal necrosis, present in our observation, occur classically in dermatomyositis where they are a predictive factor of association with neoplasia. Other recognized predictive factors are the age of the patient and persistent itching. Erythroderma linked to dermatomyositis is a very unusual event: 4 cases have been reported in the literature, only one of which was associated with cancer. On the other hand, numerous cases of diffuse erythema were reported, which are close to erythroderma. It is not possible to set out that this clinical form is a factor of bad prognosis of dermatomyositis. As a matter of fact, in the published cases, one does not find more frequent deceases, pejorative signs or increased frequency of association with neoplasia.