Pathological classification and imaging characteristics of early-stage lung adenocarcinoma with pure ground-glass opacity

Objective To discuss the pathological classification and imaging characteristics of lung adenocarcinoma with pure ground-glass opacity (pGGO).Methods Ninety-four lesions with pGGO on CT of eighty-eight patients with T1 N0M0 lung adenocarcinoma were retrospectively recruited from January 2010 to December 2012.There were 33 males and 55 females,the age ranged from 26 to 78 years with average age of (53 ± 10) years.All lesions were resected and confirmed pathologically.Among these 94 lesions,there were 21 preinvasive lesions [atypical adenomatous hyperplasia (AAH) and adenocarcinoma in situ (AIS)],35 minimally invasive adenocarcinoma (MIA)and 38 invasive adenocarcinoma.CT manifestations were analyzed including lesion location,size,density,uniformity,shape (round,oval,polygonal,irregular),margin (smooth,lobular,spiculated,lobular and spiculated),tumor-lung interface,internal and surrounding malignant signs (bubble sign,air bronchogram,pleural tag,notch).Lesion size and density were compared between different pathologic types using analysis of variance (AVOVA).Gender of patients,lesion location and CT manifestations were compared using x2-test and Wilcoxon test.The sizes of preinvasive and invasivelesions were assessed using ROC curves.Results There were no significant statistical differences ingender,lesion location and density between pathological types (P ＞ 0.05).Mean size of each group was (1.24±0.68),(1.75 ± 0.58) and (1.60 ± 0.52) cm for preinvasive lesion,MIA and invasive adenocarcinoma respectively.Lesion size of different pathologic types was significantly different (F =5.08,P =0.008).There was a significant statistical difference in lesion uniformity between pathological types (x2 =19.42,P =0.001).Three lesions of invasive adenocarcinoma(3/38)and 8 of preinvasive lesions (8/21) were of homogeneous uniformity.Thus,the more invasive the lesion was the more heterogeneity it showed.There was a significant statistical difference in margin between different pathological types (x2 =15.80,P =0.02).Preinvasive lesion always showed smooth margin(7/21),while MIA (8/35) and invasive adenocarcinoma (14/38)were more inclined to present as lobulated and speculated.Tumor-lung interface between different pathological types was significantly different (x2 =16.70,P =0.001).Well defined tumorlung interface in three groups showed as follows:38.10％ (7/21)for preinvasive lesion,77.14％ (27/35)for MIA and 86.84％ (33/38)for invasive adenocarcinoma.There was a significant difference in air bronchogram between different pathological types (x2 =6.06,P =0.048).The air bronchogram was demonstrated in 9.52％ (2/21) of preinvasive lesion,20.00％ (7/35) of MIA,and 36.84％ (14/38) of invasive adenocarcinoma.The ROC curve showed that when diameter of lesion was more than 1.05cm,the sensitivity,specificity and accuracy was 86.30％,61.90％ and 80.85％ respectively.Conclusion The lesion size,uniformity,tumor-lung interface and the air bronchogram can help predict the invasive lesion of lung adenocarcinoma with pGGO less than 3 cm. Key words: Lung neoplasms ;  Adenocarcinoma;  Pathology ;  Tomography,X-ray computed