title: Perifissural nodules seen at CT screening for lung cancer.
abstract: OBJECTIVE
  To describe and characterize the potential for malignancy of noncalcified lung nodules adjacent to fissures that are often found in current or former heavy smokers who undergo computed tomography (CT) for lung cancer screening.
  
  
  METHODS
  Institutional review board approval and informed consent were obtained. Baseline and follow-up thin-section multidetector CT scans obtained in 146 consecutive subjects at high risk for lung cancer (age range, 50-75 years; > 30 pack-year smoking history) were retrospectively reviewed. Noncalcified nodules (NCNs) were categorized according to location (parenchymal, perifissural), shape, septal connection, manually measured diameter, diameter change, and lung cancer outcome at 7(1/2) years.
  
  
  RESULTS
  Retrospective review of images from 146 baseline and 311 follow-up CT examinations revealed 837 NCNs in 128 subjects. Of those 837 nodules, 234 (28%), in 98 subjects, were adjacent to a fissure and thus classified as perifissural nodules (PFNs). Multiple (range, 2-14) PFNs were seen in 47 subjects. Most PFNs were triangular (102/234, 44%) or oval (98/234, 42%), were located inferior to the carina (196/234, 84%), and had a septal connection (171/234, 73%). The mean maximal length was 3.2 mm (range, 1-13 mm). During 2-year follow-up in 71 subjects, seven of 159 PFNs increased in size on one scan but were then stable. The authors searched a lung cancer registry 7(1/2) years after study entry and found 10 lung cancers in 139 of 146 study subjects who underwent complete follow-up; none of these cancers had originated from a PFN.
  
  
  CONCLUSIONS
  PFNs are frequently seen on screening CT scans obtained in high-risk subjects. Although PFNs may show increased size at follow-up CT, the authors in this study found none that had developed into lung cancer; this suggests that the malignancy potential of PFNs is low. (c) RSNA, 2010.
authors.affiliation: Department of Radiology, Vancouver General Hospital, 899 W 12th Ave, Vancouver, BC, Canada V5Z 1M9.
authors.forename: Myeong I
authors.initials: MI
authors.lastname: Ahn
authors.forename: Tadhg G
authors.initials: TG
authors.lastname: Gleeson
authors.forename: Ida H
authors.initials: IH
authors.lastname: Chan
authors.forename: Annette M
authors.initials: AM
authors.lastname: McWilliams
authors.forename: Sharyn L
authors.initials: SL
authors.lastname: Macdonald
authors.forename: Stephen
authors.initials: S
authors.lastname: Lam
authors.forename: Sukhinder
authors.initials: S
authors.lastname: Atkar-Khattra
authors.forename: John R
authors.initials: JR
authors.lastname: Mayo
mesh_terms: D000368:Aged; D016009:Chi-Square Distribution; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D011857:Radiographic Image Interpretation, Computer-Assisted; D013902:Radiography, Thoracic; D012189:Retrospective Studies; D012907:Smoking / Q000009:adverse effects*; D003074:Solitary Pulmonary Nodule / Q000000981:diagnostic imaging* / Q000473:pathology; D014057:Tomography, X-Ray Computed / Q000379:methods*