An unusual, recurring breast tumor with features of eccrine spiradenoma: a case report.

A new case of breast tumor with features of eccrine spiradenoma is described. This neoplasm is exceedingly rare, because only two cases, arising in breast parenchima, have been previously reported. The patient was a 43-year-old woman and she experienced three local recurrences at 7, 20, and 30 months from the first excision. No distant metastases were observed. Microscopically, the tumor was circumscribed and showed a lobulated pattern. Neoplastic lobules consisted of packed, monotonous, basaloid epithelial cells with round to ovoid nuclei and scant cytoplasm. At the periphery, the lobules were delimitated by smaller cells with dark nuclei. Immunohistochemical reactivity in tumoral cells was found for both cytokeratin and epithelial membrane antigen; vimentin, muscle-specific actin, glial fibrillary acidic protein, S-100 protein, and carcinoembryonal antigen were all negative. Furthermore, the lesion showed a diffuse positivity for estrogen and progesterone receptors and a high growth fraction labelled by MIB-1 (Ki-67) antibody. These findings, in conjunction with the deep location of the tumor, suggest an origin of the neoplasm from the breast epithelium. Because of a potential local aggressive behavior, the excision of a wide rim of uninvolved breast tissue is recommended.