THREE CASES OF BREAST METASTASES FROM LUNG CANCER AND SYSTEMATIC REVIEW OF THE LITERATURE
Metastatic involvement of the breast tissue from extramammary sites is very rare with an incidence of 0.4 -1.3 %. Despite the high rate of lung cancer among other primary tumors, metastasis of this common malignancy to the breast is very rare. We have performed a systematic review of the literature and found 258 cases published up to 2019 in English literature.
We report 3 new cases of lung cancer with breast metastases. Two were small cell lung cancer and one was an adenocarcinoma. Both breasts were affected in one case and the left breast in the other two cases. They were multiple in two cases and single in one case. Radiologically each case displayed different features. One of them had bilateral superficially and deeply located multiple irregular lesions, some of which were hyperechoic. Some also had echogenic halo around them, which is rare in metastatic tumors. Our second patient presented with findings similar to inflammatory breast cancer, such as skin and trabecular thickenning, redness over the skin and subcutaneous edema. This type of metastasis has been associated with lymphatic spread of the primary lung cancer in literature. Our third case had a circumscribed mass, resembling a benign complicated cyst. Presence of additional sites of metastases, pleural effusion and lack of spiculation and calcification were the common features in our cases. All patients died within 7-16 months after diagnosis of breast metastases.
Differentiating between metastatic and primary breast cancers is important in order to avoid unnecessary surgical procedures. Clinical history, imaging findings and immunohistochemistry may help diagnosis when used in combination. Radiologists should be aware of the spectrum of typical and atypical imaging findings of metastatic involvement of the breast to guide the clinicians for appropriate patient management.