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Paget disease of the breast is a rare form of intraductal adenocarcinoma that involves the epidermis of the nipple–areolar complex, usually associated with an underlying Ductal carcinoma in situ (DCIS) or Invasive ductal carcinoma (IDC).

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It accounts for 1–3% of all breast cancers.

Pathogenesis

• Malignant epithelial cells (Paget cells) migrate from an underlying ductal carcinoma via lactiferous ducts into the epidermis of the nipple.
• Alternatively, in situ transformation of epidermal cells has been proposed but is less widely accepted.

Histopathology

• Large, pale-staining Paget cells with prominent nucleoli within the epidermis
• Immunohistochemistry:
  • CK7 positive
  • HER2 overexpression in many cases
  • PAS-positive mucin

Clinical Features

• Unilateral eczema-like lesion of the nipple:
  • Redness, crusting, scaling, thickening
  • Nipple retraction or ulceration
  • Burning, itching, tingling
  • Serosanguinous discharge
• Lesion does not respond to topical steroids
• Often associated with palpable underlying breast mass (suggestive of invasive component)

Radiology

Differentials