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SUMMARY
Paget disease is an uncommon cutaneous neoplasm. It includes both mammary and extramammary variants.
Both variants are characterized histologically by the presence of enlarged round pale-staining Paget cells at different levels of the epidermis.
Treatment options include mastectomy or breast conservative surgery for mammary Paget disease and wide local excision or Mohs micrographic surgery for extramammary Paget disease.
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DON’T FORGET
Before treatment begins, associated malignancies should be ruled out.
Evaluation should include skin and lymph node examination, in addition to imaging studies.
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CLINICAL PEARLS
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PATIENT EDUCATION POINTS
Patients should be aware that long-term follow-up is needed as recurrences develop more than 15 years after initial treatment.
They should consult their primary health care provider for any suspicious lesion to rule out recurrent and invasive disease.
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Paget disease (PD) is classified as mammary (MPD) and extramammary (EMPD). MPD is rare and often associated with intraductal carcinoma of the breast. EMPD is considered an adenocarcinoma originating from the skin in areas with apocrine glands. It is further divided into primary or secondary subtypes based on the presence or absence of associated malignancies. Secondary EMPD is associated with underlying adnexal or internal carcinoma (Figure 24-1).1
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MPD is uncommon, representing about 1% to 4% of all breast cancer. It is extremely rare in men, with almost all cases diagnosed in women because of the predominance of breast cancer in females.2 More than 95% of MPD have an underlying breast malignancy (in situ or invasive intraductal adenocarcinoma).2
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EMPD has an incidence of 0.11 per 100,000 person-years, accounting for 7% to 14% of all cases of PD. It typically affects older individuals aged 60 to 80 years, with a peak incidence at the age of 65.3 Females are more commonly affected, with a female-to-male ratio of 3:1. Postmenopausal Caucasian women and Asian men are the predominately affected groups.3 The vulva is the typical site of involvement, accounting for approximately 65% of all cases of EMPD.4 Familial occurrence is rare, with only seven cases reported to date. However, no specific genes have been implicated so far.5
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The epidermotropic theory states that MPD represents a direct extension of malignant cells from an underlying adenocarcinoma of the breast, often HER2 positive. The intraductal cancer migrates through the basement membrane to the nipple.1,6 The second theory considers that ...