We report 3 cases of squamous cell carcinoma arising respectively after 30, 6 and 19 years of spontaneous evolution of cutaneous discoid lupus erythematosus. In each case the histopathologic examination confirmed the diagnosis of cutaneous lupus discoid and squamous cell carcinoma. As phagedenic ulcer which is the main preneoplastic dermatosis, discoid lupus erythematosis must be considered. The long duration before the cancerisation allows a correct treatment of the disease to prevent the transformation.