Paget's Disease of Nipple
Microscopically, Paget's disease shows clusters of atypical cells with voluminous clear or lightly eosinophilic cytoplasm. The cells are usually within the epidermis along the basal layer. Ultrastructurally, the cells show glandular differentiation. Immunohistochemically, they are positive for EMA, polyclonal CEA, CK7, HER2/neu, and GCDFP-15.