Pigmented mammary Paget's disease mimicking melanoma.

Our case of pigmented mammary Paget's disease simulated melanoma clinically and dermoscopically. Histologically, the lesion was characterized by microscopic features similar to those seen in malignant melanoma and, to a lesser extent, in Bowen's disease (intra-epidermal squamous cell carcinoma). Immunohistochemical studies demonstrated that the tumor cells were positive for keratins (Cam 5.2+MNF 116) and AE1-AE3 and negative for HMB-45 and S-100 proteins. In conclusion clinical and dermoscopic examination cannot reliably distinguish melanoma from epithelial pre-neoplastic or neoplastic disease, therefore the differentiation of pigmented Paget's disease from superficial spreading of melanoma and Bowen's disease is based on histopathologic integrated with immunohistochemical criteria.