The aim of this study was to underline the frequently seen problems in diag
nosing the lesions seen in the hyperplasia-carcinoma sequence by evaluating
the variances between the observers. Four pathologists re-evaluated 137 en
dometrial biopsies and grouped them into diagnostic categories. The results
were analyzed by Kappa statistics. Full agreement was reached in 89 cases
(64.96%), with Kappa values ranging between 0.63-0.74. Three observers rend
ered the same diagnosis in 34 (24.81%) cases, and only one pathologist disa
greed. Two or more observers held different views in 16 cases (10.95%). The
problem areas were as follows: criteria distinguishing simple hyperplasia
from other benign lesions, discrimination between atypical hyperplasia and
carcinoma, and decision-making regarding the presence of atypia. There was
a tendency towards overdiagnosis of hyperplasia in our department. Since th
e progression to carcinoma is a sequential event, borderline cases will exi
st if categories based on simple and clear cut off points are not defined.