CT Imaging And Clinical Features Of Micropapillary Pulmonary Ground Glass Nodules That Diameter ≤2cm

Background and Objective:With the development of imaging technology and the improvement of people’s awareness of prevention,more and more pulmonary nodules are being detected by physical examination.For malignant pulmonary nodules with ground glass on CT imaging,although most of their pathology shows low-grade malignancy,some ground glass nodules still show micropapillary subtype,and their malignancy is extremely high.Therefore,how to identify this kind of high malignant nodules from the lung ground glass nodules is particularly important.We aimed to investigate the imaging features,lymph node metastasis,and genetic mutations in micropapillary lung adenocarcinoma(imaging with mixed ground glass nodules)≤2 cm,to provide a more precise and refined basis for the selection of lung segment resection.Methods:This study was retrospective and included 162 cases from the Department of Thoracic Surgery,Shandong Provincial Hospital affiliated to Shandong University.All cases had pulmonary nodules≤2.0 cm and pathologically confirmed lung cancer after surgical resection(micropapilla mGGN 50,non-micronipple mGGN 50,and micronipple SN 62).For 100 mGGN cases,they were divided into 5 categories according to the imaging characteristics:I.cotton ball,Ⅱ.strip,Ⅲ.bubble-like lucencies,Ⅳ.lobular shape,V.Solid eccentric shape.The distribution of these five morphologies in micropapillary with mGGN and non-micropapillary with mGGN was analyzed by chi-square test or Fisher’s exact test.The postoperative pathology and prognosis of lymph node metastasis were also compared between micropapillary mGGNs and micropapillary with SNs.Meanwhile,by searching the TCGA database,a total of 196 LUAD samples with complete pathological subtypes and clinical follow-up information were obtained,including 26 micropapillary pathological subtypes and 170 samples of other pathological types.We compared micropapillary pathology subtypes with other subtypes,non-parametric tests applied Wilcoxon ranksum test while parametric tests applied analysis of variance.The differences between the two groups were analyzed using the survival package and the significance of prognostic differences between samples from different groups was assessed using the log-rank test method.Results:1.Through the analysis and study of TCGA database samples,it was found that the activity of lactate transmembrane transporter protein,collagen transcription score,and EMT score of fibroblasts in micropapillary LUAD were significantly higher than other histological types and the expression of the two genes are different.Other pathological subtypes had a better survival prognosis and longer disease-free survival compared with micropapillary adenocarcinoma.2.Among the five morphological classifications of CT imaging,either in the diameter 0-1.0cm,1.0-1.5cm group or in the 1.5-2.0cm group,all were statistically different(P<0.05).In group 0-1.0cm,non-micropapillary pattern GGN was only distributed in type I.type II and type III,and the proportion was 63.6%,18.2%,and 18.2%,respectively;Micropapillary pattern GGN was mainly distributed in the type Ⅳ,type Ⅴ,with 27.3%and 35.5%,respectively.Distribution was also statistically different in the 1.0-1.5cm and 1.5-2.0cm groups,with P-values of 0.016 and 0.006,respectively.In addition,micropapillary pattern GGN is mainly concentrated in type Ⅳ,Ⅴ,while non-micropapillary pattern GGN is mostly concentrated in type Ⅰ,Ⅱ.3.In the comparison of postoperative pathological lymph node metastasis between micropapillary and non-micropapillary mGGN,it was 26%for micropapillary mGGN and 2%for non-micropapillary mGGN,and there was a significant statistical difference(P=0.001).4.In the comparison of postoperative pathological lymph node metastasis between micropapillary mGGN and SN,the rate was 26%for micropapillary mGGN and 32.3%for micropapillary SN.Conclusion:1.micropapillary subtype LUAD has obvious heterogeneity and higher malignancy compared with other subtypes of LUAD,and LUAD of micropapillary subtype has a worse prognosis.2.The 5 CT morphological classifications can help us to distinguish the extremely dangerous micropapillary pattern mGGN from mGGN.In general,type Ⅰ and type Ⅱ are usually non-micropapillary mGGN with low risk;Type Ⅲ may be micropapillary pattern mGGN,so it can be regarded as a warning factor;It is highly likely that type Ⅳ and V are micropapillary pattern mGGN,and it is a high-risk factor.3.Micropapillary mGGN has a high risk of lymph node metastasis compared with non-micropapillary mGGN and should be highly vigilant.4.Micropapillary mGGN compared with micropapillary SN,overall,the rate of postoperative pathological lymph node metastasis of micropapillary SN was higher than that of micropapillary mGGN,but the lymph node metastasis rate of micropapillary mGGN is still relatively high.