[Paget's disease of the nipple and differential diagnosis]

Clinical evaluation of the nipple-areolar complex is a routine component of the breast screening examination. All persistent unilateral nipple lesion should be viewed with suspicion and Paget's disease of the nipple should be considered. The diagnosis is established by nipple scrape cytology. It is a rare variant of ductal carcinoma in situ. The breast imaging work-up should include a search for an underlying malignancy, present in over 80% of cases, not infrequently multifocal. Preoperative MRI is useful if breast conservative surgery is contemplated because of the high rate of occult malignancy on mammograms and ultrasound. Erosive adenomatosis of the nipple is a benign process that may simulate Paget's disease isolated to the nipple. Less frequently, pagetoid basal cell carcinoma, Bowen's disease and melanoma may be more difficult to differentiate clinically and share the unilateral and chronic features of Paget's disease. Biopsy is needed for diagnosis. Cutaneous extension of a breast cancer is rare but should be suspected in patients with retraction and/or fixed nipple. Eczema is characterized by the bilateral nature of the process, the absence of nipple deformity, the presence of flare-ups and the favorable response to local steroid therapy.