Uncommon intraepithelial adenocarcinoma occurring in apocrine gland-bearing skin in patients older than age 50 years.
Erythematous, scaly plaque frequently misdiagnosed as inflammatory or infectious dermatitis.
Most commonly affected sites: unilateral nipple/areola (mammary Paget’s disease [MPD]); vulva, perianal skin, scrotum, and penis (extramammary Paget’s disease [EMPD]).
Nearly all cases of MPD are associated with underlying breast carcinoma; EMPD is associated with underlying cancer in a minority (20% to 30%) of cases.
Mammary Paget’s disease (MPD; also called Paget’s disease of the breast) is an intraepidermal adenocarcinoma of the nipple and/or areola, typically associated with underlying breast carcinoma. Extramammary Paget’s disease (EMPD) is a clinically distinct condition that affects extramammary sites, such as the vulva, penis, scrotum, perineum, and anus. Even though both MPD and EMPD may appear similar clinically and histologically, they differ in their pathogenesis and frequency of associations with underlying malignancies.
In 1874, Sir James Paget first reported MPD in a series of 15 women with chronic dermatitis of the nipple and areola who were subsequently diagnosed with underlying breast carcinoma.1 In 1889, English dermatologist Henry Racliffe Crocker first described EMPD as a condition on the scrotum and penis with histopathology similar to MPD.2
MPD represents approximately 1% to 3% of breast cancers.3 The peak incidence is between 50 and 60 years of age, with most reported cases occurring in women. In various studies, between 82% and 100% of MPD cases are associated with an underlying in situ or invasive ductal carcinoma.3
EMPD is a rare malignancy of the anogenital region, with various studies citing incidence rates ranging from 0.6 per 1,000,000 person-years to 0.11 per 100,000 person-years.4,5 The majority of cases occur in the sixth through eighth decades of life, with women more commonly affected than men.6-8 In contrast to MPD, most cases of EMPD are not associated with an underlying adnexal carcinoma or visceral malignancy, with most studies reporting approximately a 20% to 30% risk.7
Both MPD and EMPD present with a longstanding history of erythematous, scaly, or velvety patches or plaques on the breast and anogenital skin, respectively. The most commonly reported symptom is pruritus. Other symptoms may include pain, bleeding, a burning sensation, and serosanguinous discharge. Because of the rather nondescript appearance, there is often a several-month delay in diagnosis as initial treatment frequently involves topical steroids (for presumed inflammatory dermatitis) or antifungal agents (for presumed infectious dermatitis).
MPD frequently presents as a unilateral, erythematous, scaly plaque involving the nipple and/or the areola (Fig. 114-1). The associated pruritus may lead to lichenification and excoriations. Ulceration, weeping, and ...