Primary lung adenocarcinoma is classified according to predominant histopathologic architecture into lepidic, papillary, acinar, solid, and micropapillary subtypes. These subtypes are related to overall survival in primary lung adenocarcinoma. The main goal of our work was to evaluate the prognostic impact of this classification on surgical resection of brain adenocarcinoma metastases in 97 patients with surgically resected brain metastases of lung adenocarcinoma from 2008 to 2017. Histopathologic subtype is associated with overall survival (P=0.0085): 30.1±5.6 months for papillary-predominant pattern, 26.5±6.3 months for acinar-predominant pattern, 13.8±1.4 months for solid pattern, 11.6±10.1 for micropapillary pattern. A "low grade" group comprising acinar and papillary-predominant pattern tumors showed a longer overall survival (28.5±4.1 mo) when compared with high-grade-predominant pattern (solid and micropapillary patterns) (13.7±1.4 mo), P=0.0011. On multivariate analysis, age below 55 years at the time of resection (hazard ratio, 3.56; 95% confidence interval, 1.12-11.31) and groups of architectural patterns (hazard ratio, 4.25; 95% confidence interval, 1.83-9.9) were related to overall survival (P=0.031 and 0.00078, respectively). Predominant architectural pattern evaluated on the surgical specimen of brain metastasis is a major prognostic factor of overall survival in metastatic lung adenocarcinoma.