Paget Disease of the Breast
Definition
-
Intraepithelial involvement of the nipple by breast carcinoma cells
Alternate/Historical Names
- Mammary Paget disease
- Paget disease of the nipple
Diagnostic Criteria
- Intraepithelial population of large atypical cells (Paget cells)distinct from surrounding normal epithelial cells
- Large nuclei, prominent nucleoli
- Abundant pale to amphophilic cytoplasm
- Scattered individually and in clusters
- Epidermal hyperplasia and hyperkeratosis and parakeratosis frequently present
- May result in pseudoepitheliomatous hyperplasia
- Underlying chronic inflammation common
- Phenotype is similar to breast carcinoma
- Mucin stain occasionally positive
- CK7 highlights Paget cells
- Melanin is detectable in Paget cells in rare cases
- Underlying in situ or invasive breast carcinoma is found in nearly every case
- May require extensive examination of breast tissue
- Nearly always ductal type
