Eccrine ductal and acrosyringeal metaplasia in breast carcinomas: report of eight cases.

Eccrine ductal and acrosyringeal metaplasia was described in 2006 as the presence of tumor structures that resemble the epithelium of the eccrine skin ducts and their opening within the epidermis, the acrosyringeum. Here, we report the clinical, morphological, and phenotypic characteristics of eight breast carcinomas that we collected over the past years showing this metaplasia. Unlike squamous metaplasia, acrosyringeal and eccrine ductal metaplasia are luminated structures comprising cells with eosinophilic cytoplasm that are easily detectable in routine histological slides. These lesions invariably appeared in triple-negative carcinomas, but the cases differed in their clinical, radiological, and histological manifestations. Correct interpretation of these changes may facilitate identification of some metaplastic carcinomas.