title: Differences in the structural features of atypical adenomatous hyperplasia and low-grade prostatic adenocarcinoma.
abstract: OBJECTIVE
  Atypical adenomatous hyperplasia (AAH) is a small glandular proliferation that has histological similarities with Gleason grade 1 and 2 prostatic adenocarcinoma (PACG1,2). There are no distinct histomorphological criteria distinguishing these two lesions from each other and other small glandular proliferations. Because treatment approaches are different for these lesions, it is necessary to determine histological criteria. The aim of this study is to review the histological features of these two lesions and to define new histological criteria distinguishing AAH from PACG1,2. We, therefore, assessed 18 anatomical and structural parameters.
  
  
  METHODS
  We found 11 AAH (22 foci) and 15 PACG1,2 (22 foci) cases in 105 radical prostatectomy specimens. Basal cell-specific antikeratin was applied to these lesions. We assumed that PACG1,2 lesions did have not basal cells and we grouped the lesions as AAH and PACG1,2 based on this assumption.
  
  
  RESULTS
  We found differences between AAH and PACG1,2 lesions for some parameters including the number of glands, structures such as the main ductus and basal cells. We found similar properties in the two lesions for the following parameters: localization, multiplicity, diameter of the lesion, focus asymmetry, distance between glands, inflammatory cells in and out of the lesions, secretory cell shape on the luminal side, papillary projection towards the luminal side of gland, the shape of the outer gland, the infiltrative pattern of the gland, glandular pleomorphism, biggest gland diameter and median gland diameter.
  
  
  CONCLUSIONS
  We determined that concurrent evaluation of histomorphological features was important to differentiate between AAH and PACG1,2.
authors.affiliation: Department of Pathology, Marmara University Hospital, Istanbul, Turkey.
authors.forename: Ahmet
authors.initials: A
authors.lastname: Midi
authors.forename: Tülay
authors.initials: T
authors.lastname: Tecimer
authors.forename: Süheyla
authors.initials: S
authors.lastname: Bozkurt
authors.forename: Naziye
authors.initials: N
authors.lastname: Ozkan