What are the cells of origin and the immunohistochemical profile of Paget disease?
The Paget cells (intraepithelial large cells with pale pink cytoplasm and large nuclei) are believed to be of apocrine lineage and show immunoreactivity with low-molecular-weight keratins Cam 5.2, CK7, and carcinoembryonic antigen. Mucin stain may be positive. The differential diagnosis includes pagetoid spread from adjacent CRC and melanoma in-situ. The immunoprofile helps.