[Clinicopathological features of acantholytic mammary Paget's disease: a report of 28 cases].

To investigate the clinicopathological features of acantholytic mammary Paget's disease (AMPD). From January, 2010 to October, 2016, a total of 28 patients were diagnosed as AMPD in the Department of Dermatology, Peking Union Medical College Hospital. The clinical and histopathological data of these patients were analyzed retrospectively. The patients were all female. The mean age of onset was (51±15)years (range, 24 to 78 years). The median course of disease was 10.5 months (range, 3 months to 2 years). All the cases were unilaterally involved. The ratio of left breast involvement to the right breast involvement was 1.55∶1. In histopathological examination, all the cases showed acantholytic pattern. In addition to that, the prototypical pattern accounted for 50.0% (14/28) of all the AMPD cases. The frequencies of other different accompanied histopathological patterns were: 3 (10.7%) upper nest, 2 (7.1%) budding, 1 (3.6%) tall nest, and 1 (3.6%) sheet-like. Hailey-Hailey-disease-like acantholysis was observed in 18 patients (64.3%), whereas pemphigus-vulgaris-like acantholysis was noted in 7 patients (25.0%) and Darier's-disease-like acantholysis in 3 patients (10.7%). About 75.0% (21/28) of the AMPD cases were found to be accompanied with underlying breast cancers. There was no recurrence in 18 of 20 patients who completed treatment and were followed up for over 1 year. AMPD might involve the left breast more frequently. It is mostly associated with the prototypical pattern of mammary Paget's disease. Hailey-Hailey-disease-like acantholysis may be the most frequent subtype of AMPD. Most AMPD cases are associated with underlying breast cancers, but with a low recurrence rate after treatment.