Apocrine adenoma of the breast coexistent with invasive carcinoma

We describe a case of apocrine adenoma with simultaneous occurrence of invasive ductal carcinoma in the breast of a 53-year-old woman. Apocrine adenoma affecting the breast is very rare. The lesion is composed of back-to-back ducts and papillary fronds covered with apocrine cells, and it is sharply demarcated from the surrounding breast tissue. The patient presented with a palpable nodule with skin retraction in her right breast, where ultrasound examination identified a 5-mm hypoechogenic nodule. The ultrasound also revealed in the surrounding breast parenchyma an additional abnormal finding suggestive of carcinoma. Histologic examination of the excised specimen showed that the hypoechogenic nodule represented an apocrine adenoma in proximity to the invasive ductal breast carcinoma. This is the first report that describes the simultaneous occurrence of these two lesions in the same breast.