A case of endobronchial pagetoid spread of a breast carcinoma metastatic to the lung is described. A 73-year-old woman underwent wedge lung resection after the cytological diagnosis of lung metastasis from ductal invasive breast carcinoma. The breast carcinoma had been surgically removed 6 years previously; at the time of diagnosis it was a T1N0, grade 3 invasive ductal carcinoma, with HER-2 amplification. The lung metastasis measured 1,9 cm and showed the same histology and biological profile of the primary tumor. In addition, numerous neoplastic cells, with large cytoplasm and atypical nuclei, appear to spread along the mucosa of the bronchi adjacent to the metastatic lesion as well as that of the main lobar bronchus, intermingled with the columnar ciliated cells. The neoplastic elements were negative for TTF-1 and strongly HER-2 positive; these features appeared consistent with endobronchial pagetoid spread by the metastatic breast carcinomatous cells.
Keywords: HER-2 amplification; breast cancer; endobronchial pagetoid spread; metastatic breast cancer.