title: CT findings and progression of small peripheral lung neoplasms having a replacement growth pattern.
abstract: OBJECTIVE
  We investigated the imaging findings and progression of replacement lung neoplasms that were revealed on thin-section CT and serial CT.
  
  
  METHODS
  We evaluated the age of patients and thin-section CT findings (lesion size; percentage of ground-glass opacity areas; and presence or absence of solid portions, lobulation, coarse spiculation, air bronchogram, cavity, multiplicity, and pleural tags) in 73 lesions (11 atypical adenomatous hyperplasias, 17 type A [Noguchi's classification], 18 type B, and 27 type C small peripheral adenocarcinomas). We compared the serial findings of 48 of 73 lesions on low-dose screening CT (n = 21) or thin-section CT (n = 27) obtained at a mean interval of 450 days (range, 85-951 days). Progression from atypical adenomatous hyperplasia through type A to type B and then to type C tumor was studied using trend tests.
  
  
  RESULTS
  A significant linear trend was seen for lesion size (r = 0.55; p < 0.001), percentages of ground-glass opacity areas (r = 0.75; p < 0.001), and the prevalence of lobulation (p < 0.001), spiculation (p = 0.001), air bronchogram (p = 0.023), cavity (p = 0.046), pleural tag (p < 0.001), and solid portions (p < 0.001). In general from serial CT assessment, lesions were recognized first as a ground-glass opacity nodule (56% of 48 lesions) with subsequent increase in size (75%), then solid portions appeared in the nodule (17%), and finally solid portions increased (23%) with occasional augmentation of tissue contraction (6%).
  
  
  CONCLUSIONS
  CT analysis revealed stepwise progression of replacement-type lung neoplasms.
authors.affiliation: Department of Radiology, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto 390-8621, Japan.
authors.forename: Shodayu
authors.initials: S
authors.lastname: Takashima
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Maruyama
authors.forename: Minoru
authors.initials: M
authors.lastname: Hasegawa
authors.forename: Takeshi
authors.initials: T
authors.lastname: Yamanda
authors.forename: Takayuki
authors.initials: T
authors.lastname: Honda
authors.forename: Masumi
authors.initials: M
authors.lastname: Kadoya
authors.forename: Shusuke
authors.initials: S
authors.lastname: Sone
mesh_terms: D000230:Adenocarcinoma / Q000000981:diagnostic imaging* / Q000473:pathology*; D000328:Adult; D000368:Aged; D018450:Disease Progression; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D014057:Tomography, X-Ray Computed