〔Abstract〕 Objective To investigate the correlations among clinicopathological features, histopathological growth patterns and prognosis of extrapulmonary multiple metastatic(stage ⅣB) pulmonary adenocarcinoma with epidermal growth factor receptor(EGFR) mutations. Methods A total of 488 eligible patients with adenocarcinoma of stage ⅣB. Clinicopathological data,EGFRgene mutation subtypes, metastatic sites, histopathological growth patterns and survival information were collected. The chi-square test(χ2test) and Fisher's exact probability method were used to detect the correlation between the metastasis status and various clinical characteristics; the Kaplan-Meier method was used to conduct survival analysis on the median Progression-Free Survival(PFS) under different clinical characteristics. Cox univariate and multivariate regression analyses were conducted to evaluate the impact of various clinical characteristics on prognosis. Results The metastatic patterns of stage ⅣB pulmonary adenocarcinoma withEGFRmutations was correlated with histopathological growth patterns(P<0.05). In the group with multiple metastases in a single organ, the proportion of micropapillary type in the group with multiple metastases in a single organ was higher than that in the group with multiple-organ metastases(51.1%vs41.1%), while the proportion of solid type in the group with multiple-organ metastases was higher than that in the group with multiple metastases in a single organ(23.8%vs14.2%). Multiple brain or multiple bone metastases were correlated with histopathological growth patterns and tumor differentiation degree. Compared with the multiple bone metastases group, the proportion of acinar type decreases in the multiple brain metastasis group, while the proportion of micropapillary type increased. Moreover, the proportion of poorly differentiated tumors increased significantly(P<0.05). Compared with multiple bone metastases, the proportion of poorly differentiated tumors significantly increases in the group with multiple brain metastases. The median progression-free survival(PFS) of patients with a predominant solid growth pattern was shorter than that of patients with other growth patterns(12.7 monthsvs17.8 months,P<0.05). The PFS of patients in the poorly differentiated group was worse than that in the moderately differentiated group(15.6 monthsvs17.8 months,P<0.05). There were significant differences in PFS among patients with common sensitive mutations and rare mutationsEGFR(17.3 monthsvs10.2 months,P<0.01). Cox proportional hazards regression model suggested that solid growth pattern, poor differentiation and rare single gene mutation were adverse prognostic factors. Conclusion In stage ⅣB pulmonary adenocarcinoma patients withEGFRmutations, both the metastatic patterns and metastatic sites are significantly correlated with the histopathological growth patterns of tumors. Moreover, theEGFRmutation subtypes as well as the histopathological growth patterns and differentiation degree of tumors significantly affect the prognosis of patients.