title: Early lung cancer with lepidic pattern: adenocarcinoma in situ, minimally invasive adenocarcinoma, and lepidic predominant adenocarcinoma.
abstract: OBJECTIVE
  This review gives a comprehensive overview on recent developments in the classification of neoplastic lung lesions with lepidic growth patterns, comprising the adenocarcinoma (ADC) precursor lesions atypical adenomatous hyperplasia (AAH), adenocarcinoma in situ (AIS), and minimally invasive adenocarcinoma (MIA) as well as lepidic predominant adenocarcinoma (LPA).
  
  
  RESULTS
  The concept of a continuum between the precursor lesions AAH and AIS to MIA and frankly invasive ADC is backed by a wealth of recent data showing a gradual decrease in overall survival from 100% for AAH, AIS, and MIA to moderately lower rates for LPA. Further, it has been shown that the morphologic categorization of these tumors can be done with reasonable reliability and that nonmucinous lepidic tumors show distinct molecular alterations with high rates of epidermal growth factor receptor mutations. Importantly, lepidic tumor growth is also mirrored by specific characteristics in computed tomography images, arguing for a combined assessment of histomorphology and imaging data for an optimized classification of lepidic neoplasms.
  
  
  CONCLUSIONS
  The validity and clinical importance of the novel concept of ADC precursor lesions and LPA have been confirmed by clinical, radiological, morphological, and molecular data. Thereby, it has evolved into a valuable tool to aid in clinical decision-making.
authors.affiliation: Institute for Pathology, Heidelberg University, Heidelberg, Germany.
authors.forename: Wilko
authors.initials: W
authors.lastname: Weichert
authors.forename: Arne
authors.initials: A
authors.lastname: Warth
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology*; D065311:Adenocarcinoma in Situ / Q000473:pathology*; D000077192:Adenocarcinoma of Lung; D003657:Decision Making; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology*; D009361:Neoplasm Invasiveness; D009364:Neoplasm Recurrence, Local; D009367:Neoplasm Staging; D011379:Prognosis; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed