Paget Disease of the Breast

Supplemental Studies

CK7 is the most useful marker as it is not expressed by the surrounding epidermal cells
- Normal Toker cells and Merkel cells are positive for CK7 and must be distinguished morphologically
- CAM5.2 may be useful as a substitute as it is nearly as specific
Other anti-keratins and EMA will stain most Paget cells but are not as specific
High molecular weight cytokeratin (HMWCK) and p63 are useful complementary markers
- Squamous carcinoma in situ is nearly always positive while Paget cells are nearly always negative
S100 may be expressed by Paget cells so it is not a perfect marker to rule out melanoma
ER and PR are variably expressed