Paget disease of the nipple

Eczema-like changes in the skin of the NAC, in association with an underlying breast cancer

Epidemiology

• Accounts for <1% of breast malignancies
• 90% of patients with Paget disease have an underlying breast carcinoma

Pathophysiology

• Paget cell - large, pale-staining cell with round or oval nuclei and large nucleoli located between the normal keratinocytes of the nipple epidermis
• Theories of development
  • Epidermotropic - perhaps more likely - Paget cells spread into the lactiferous sinuses under the nipple and upward to invade the overlying epidermis of the nipple
  • In-situ transformation - less likely
• Paget cells do not invade through the basement membrane, and are categorised as carcinoma-in-situ
• Commonly associated with an underlying breast cancer, often in the large sinuses just under the nipple
  • Most likely HER2+ and hormone negative
  • 90% IDC, 10% DCIS

Presentation

• Dermatitis of the nipple - appears eczematoid and moist or dry and psoriatic.
• About half have an underlying breast mass

Differential diagnosis

• Eczema - usually spares the nipple itself
• Contact dermatitis
• Post-radiation dermatitis

Workup

• Punch/core biopsy of nipple skin, under LA
  • Specimen containing Paget cells confirms the diagnosis (pathognomic finding)
• Thorough investigation for occult malignancy, especially for patients having BCS
  • Mammogram/USS
  • Proceed to MRI if concerning presentation and other imaging normal

Treatment options

• Mastectomy with axillary staging
• Wide local excision of the nipple and areola with axillary staging and radiotherapy