Metastases to the breast from extramammary malignancies: a clinicopathologic study of 12 cases.

Along with a brief review of the literature, we report the clinicopathologic features of 12 cases of extramammary malignancies metastatic to the breast. Histological diagnoses of the primary tumor were as follows: non-Hodgkin diffuse large B-cell lymphoma (3 patients), acute mycloid leukemia (3 patients), serous papillary adenocarcinoma, well-differentiated adenocarcinoma, squamous cell carcinoma, undifferentiated neoplasm, mesothelioma, and melanoma. The most common mammographic finding was a well-circumscribed mass with increased density but without speculation, calcifications or other signs that characterize the majority of primary carcinomas. Ultrasound revealed well-circumscribed masses without retrotumor acoustic shadowing. The interval between diagnosis of primary cancer and the appearance of breast metastasis ranged from 0 to 108 months (mean: 17, median: 1). Survival after the detection of the breast metastases ranged from 0.2 to 144 months (mean: 23, median: 9.5). In conclusion, metastasis can mimic either benign disease or primary malignancy and is often an unexpected diagnosis in a patient presenting with a breast mass. Thus, an accurate diagnosis is important to avoid unnecessary mutilating surgery. These masses generally indicate disseminated metastatic disease, with a very poor survival rate.