A twenty-six-year-old woman with a two-year history of an erythematous, scaly lesion on the left nipple was being followed up by her gynecologist and treated using a topical corticoid for chronic eczema albeit with no improvement. She was referred to this department where a diagnosis of Paget's disease of the breast associated with a ductal carcinoma in situ was made. Paget's disease is uncommon prior to the fourth decade of life and the great majority of cases are associated with breast carcinomas. Differential diagnosis must be made between this condition and nipple eczema. As shown in the present case report, late diagnosis results in poor prognosis and higher morbidity since mutilating procedures then become necessary.