RESUMO
<p><b>OBJECTIVE</b>To explore the clinicopathological characteristics and imaging features of lung adenocarcinoma with a micropapillary pattern (MPP).</p><p><b>METHODS</b>Eighty cases of pulmonary adenocarcinoma with a micropapillary pattern treated in our hospital from July 2011 to December 2012 were selected to retrospectively analyze their clinicopathological characteristics and imaging features.</p><p><b>RESULTS</b>Among the 80 cases of lung adenocarcinoma with MPP, there were 38 cases of stage I (47.5%), 12 cases of stage II (15.0%), 25 cases of stage III (31.3%) and 5 cases of stage IV (6.2%). There were 14 cases of moderately differentiated (17.5%) and moderately/poorly differentiated (82.5%) tumors. Sixty-three cases had pleural involvement, vascular invasion, involving the bronchial wall, invasion of large vessels, nerve invasion, and lymph node metastasis (at least one of them) (78.8%). Immunohistochemical staining revealed that both positive rates of TTF-1 and CK7 were 100%, and that of pulmonary surfactant apolipoprotein-A (SPA) was 84.0%. Imaging examination revealed hilar or mediastinal lymph node enlargement in 15 cases (18.8%). but the pathology confirmed hilar or mediastinal lymph node metastasis in 36 cases (45.0%). Lung CT imaging showed that the majority of the cases were peripheral type, and only a few of central type, and most cases were solid lesions, with lobulation, spiculation, pleural indentation, and vascular convergence sign, while there were few ground-glass opacity sign and vacuole sign.</p><p><b>CONCLUSIONS</b>Lung adenocarcinoma with MPP component often presents with early invasions of pleura, blood vessels, lymphatic vessels, and lymph nodes. Imaging manifestation of this cancer mainly shows as peripheral and solid lesions, often with lobulation, spiculation, pleural indentation, vascular convergence sign, but GGO and vacuole signs are unusual. Overexpression of TTF-1, CK7 and SPA, and elevated CEA level are associated with clinical staging of the disease.</p>