Giant Apocrine Hidradenoma of the Breast

We report a case of a 26-year-old woman with an 8.0-cm tumor of the left breast. The tumor was clinically and radiologically suspicious for malignancy. The pathologic evaluation of the core biopsy and the subsequent excision specimen revealed a benign sclerosing, cystic, and papillary adnexal tumor with apocrine and clear cell morphology. The immunohistochemical staining for p63 was positive. Estrogen, progesterone, and Her-2 receptor immunohistochemical stains were negative. The cytogenetic analysis revealed 46, XX t(11:19) (q21;q13.1) balanced translocation. The final diagnosis was apocrine hidradenoma.