The following breast lesion was found on skin biopsy. Deeper biopsies performed for calcifications showed ductal carcinoma in situ (DCIS). Which is true regarding the pictured lesion?

  • Incorrect. The lesion is present in 1-2% of patients with breast carcinoma.

  • Incorrect. The history and morphology are more consistent with Paget’s disease of the nipple than melanoma. Paget’s disease is positive for CK7 and Her2, and more frequently negative for ER and PR.

  • Incorrect. Tumor cells of Paget’s disease of the nipple are positive for low molecular weight cytokeratins (Cam 5.2, CK AE1/AE3), CK7, Her2, and androgen receptor. They are variably positive for ER and PR, but are usually negative, the same as the underlying tumor.

  • Incorrect. Paget’s disease is not considered skin invasion for the purposes of staging. DCIS in conjunction with Paget’s is staged as “pTis (Paget’s)”.

  • Correct. Paget’s disease of the nipple is considered to be an situ lesion. The prognosis is dependent on the characteristics of the underlying lesion.