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PAGET DISEASE

Paget disease typically occurs on the female nipple (Figs 33.49 - 33.51), where it is formed by cutaneous spread from an intraductal carcinoma of the underlying breast tissue. Rarely, lesions occur in the groin or perineum (extramammary Paget disease, Figs 33.52 and 33.53), which usually represent an intraepithelial carcinoma arising from dermal apocrine glands, but are occasionally related to urinary tract neoplasia.
    Paget disease at these sites presents as a well-defined, moist or crusted, erythematous plaque that clinically resembles Bowen disease. This similarity may also be apparent histologically, as both disorders cause intraepithelial balloon cells, but in Paget disease the cells stain positively with periodic acid Schiff or mucin stains.

Figure 33.51  Paget disease: a neglected lesion with extensive involvement of the skin of the breast.

Figure 33.52  Extramammary Paget disease in the groin crease in a man. This lesion was treated for 8months as unilateral intertrigo.

Figure 33.53  Extramammary Paget disease of the perineum. This may be asymmetric around the natal cleft, by comparison with eczemas, which are usually symmetric.

    On the breast, the differential diagnosis is primarily from eczema of the nipples, but this is almost always bilateral (although not always symmetric), whereas Paget disease is unilateral. Note that nipple eczema is not rare; indeed, it is a minor diagnostic criterion for atopic eczema. In the perineum, the differential diagnosis is primarily from pruritus ani with eczematization, or from perianal Bowen disease (also rare). Carcinoembryonic antigen is usually positive in skin biopsies from Paget disease, and a tumor marker termed RCAS1 has been suggested as a useful marker in extramammary Paget disease.

Figure 33.54   Merkel cell carcinoma. This small lesion occurred in an immunosuppressed transplant patient and grew rapidly. The prognosis for this tumor is generally poor, particularly in immunosuppression.

Figure 33.55  Merkel cell carcinoma on the cheek, with an obvious nodal metastasis at the time of presentation.

    Treatment is usually surgical, to include the underlying neoplasm. Radiotherapy and photodynamic therapy have a role in some cases.

PRACTICE POINTS

White/Cox: Diseases of the Skin, 2ed.(c) 2006, Elsevier Inc. All rights reserved.