Anaplastic Paget's disease.

Six cases of a distinct, histologically anaplastic variant of mammary Paget's disease are described. Patients ranged in age from 40 to 85 years. All patients had scaling erythematous lesions confined to the nipple; none had palpable breast masses. Histologically, the lesions had features resembling Bowen's disease, including full-thickness epidermal atypia, loss of nuclear polarity, and marked cytologic anaplasia. Intraepidermal acantholysis was a distinctive feature in all cases. In some biopsies, small groups and single typical Pagetoid cells were seen within the areas of confluent Bowen-like change. Immunohistochemically, carcinoembryonic antigen (CEA) was positive in three of six patients; epithelial membrane antigen (EMA) in five of six patients, and cytokeratin AE1/AE3 in three of six patients. Mucicarmine stains were uniformly negative. In our series, anaplastic Paget's disease was associated with concomitant invasive ductal carcinoma in three of six patients (50%). This percentage is significantly higher than that previously reported for patients with Paget's disease and without palpable breast mass. Histologic features that are helpful in distinguishing between anaplastic Paget's disease and Bowen's include cleft-like acantholysis, absence of dyskeratotic cells, and persistence of basal cell layer. More rarely, but very helpful when present, are underlying ductal carcinoma, intracellular lumina, and associated conventional Paget's disease. Immunohistochemistry results were variable and of relative value. Our study suggests that a nipple lesion histologically resembling Bowen's disease is likely to represent anaplastic Paget's disease.