Subsequent work-up included a staging magnetic resonance imaging (MRI) and a left areola punch biopsy. MRI revealed an absence of a normal left nipple and extensive focal clumped non-mass enhancement in the area of the known DCIS (FIGURE 4). Biopsy results revealed enlarged atypical single cells within the epidermis. The cells stained positive for mucicarmine and cytokeratin 7 and negative for carcinoembryonic antigen and S-100 protein. This ruled out a pagetoid spread of melanoma and confirmed a diagnosis of Paget’s disease (PD) of the breast.
DISCUSSION
PD of the breast is a rare disorder (accounting for 0.5%-5% of all breast cancers) that is clinically characterized by erythematous, eczematous changes of the nipple-areolar complex (NAC).1-7 PD is almost always unilateral and symptoms include pain, burning, and itching of the nipple, often with bloody nipple discharge.1,3-8
PD can be mistaken for benign skin changes and diagnosed as dermatitis or eczema.3,5 Because such changes often resolve temporarily with the use of topical corticosteroids or no treatment at all,2 diagnosis is often delayed. PD of the breast is associated with underlying ductal carcinoma in 90% to 100% of cases,1,2,5,8 so any skin pathology involving the nipple should be assumed to be PD until proven otherwise.
When no palpable mass is noted on physical exam, DCIS is usually found centrally behind the nipple.1 In addition, lymph node involvement is noted in about 60% of cases.1
Confirm the diagnosis with these tests
Diagnosis of PD of the breast is primarily clinical, with pathologic confirmation. All patients with clinically suspected PD should be evaluated using the following tests to determine the need for biopsy.
Mammography with magnification views of the NAC will show thickening, retraction, or flattening of the nipple, microcalcifications of the retroareolar region, and/or a subareolar mass.3 However, because breast tissue appears normal on mammography in 22% to 71% of patients,1,5 the use of ultrasound and potentially MRI to delineate the extent of disease is warranted.