title: Adenocarcinoma in situ with a small cell (endometrioid) pattern in cervical smears: a test of the distinction from benign mimics using specific criteria.
abstract: BACKGROUND
  Papanicolaou smears have been less effective in preventing cervical adenocarcinoma than in preventing squamous carcinoma. One reason may be a lack of awareness of certain smear patterns of adenocarcinoma in situ (AIS) such as those with crowded small cells (endometrioid pattern).
  
  
  METHODS
  A test set of 29 smears (17 AIS with an endometrioid pattern, 12 benign mimics) was reviewed by 11 cytologists (4 experienced cytotechnologists, 3 cytopathology fellows, and 4 cytopathologists with varying levels of experience). Participants were blinded as to the actual diagnosis and the number of cases in each category and were instructed to diagnose either AIS or a benign lesion. Results of this review were not disclosed before a second review conducted after instruction in specific criteria for "endometrioid" AIS. Results were compiled using kappa statistics.
  
  
  RESULTS
  In the first round, the ability to distinguish these lesions was poor for 8 of the 11 reviewers, and no reviewer was in excellent agreement with the actual diagnosis. In the second round, only 1 reviewer had a poor rating, and 4 of 11 were in the excellent category. Misdiagnoses in both rounds were more commonly the result of underdiagnosis of AIS than overdiagnosis of benign cases.
  
  
  CONCLUSIONS
  The presentation of AIS in smears as groups of crowded small cells is prone to underdiagnosis. Awareness of this problem and use of criteria improves sensitivity. [See editorial on pages 243-4, this issue.] Cancer (Cancer Cytopathol)
authors.affiliation: Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA.
authors.forename: K R
authors.initials: KR
authors.lastname: Lee
mesh_terms: D018269:Carcinoma, Endometrioid / Q000473:pathology*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D015588:Observer Variation; D065006:Papanicolaou Test; D011237:Predictive Value of Tests; D002583:Uterine Cervical Neoplasms / Q000473:pathology*; D014626:Vaginal Smears