Reproducibility of new classification schemes for the pathology of ductal carcinoma in situ of the breast.
OBJECTIVE
To compare the interobserver variation in the pathological classification of ductal carcinoma in situ of the breast using two recently proposed classification schemes.


METHODS
11 pathologists classified a set of 25 cases of ductal carcinoma in situ chosen to reflect a range of lesions, using the traditional architectural classification together with the modified cytonuclear grading scheme of Holland et al and the Van Nuys classification scheme. Participating pathologists received a standard tutorial, written information, and illustrative photomicrographs before their assessment of the cases.


RESULTS
Interobserver agreement was poorest when using the architectural scheme (kappa = 0.44), largely owing to variations in classifying lesions with a mixed component of patterns (kappa = 0.13). Agreement was better using the modified cytonuclear grading scheme (kappa = 0.57), with most consistency achieved using the Van Nuys scheme (kappa = 0.66). Most discordant results using the later scheme were due to inconsistency in assessing the presence or absence of luminal necrosis.


CONCLUSIONS
Both the new classification schemes assessed in this study were an improvement over the traditional architectural classification system for ductal carcinoma in situ, and resulted in more reproducible pathological assignment of cases. The Van Nuys classification scheme is easy to apply, even to small areas of carcinoma, resulting in acceptable interobserver agreement between reporting pathologists. Additional work will be required to arrive at a consensus definition of necrosis for cases in the non-high-grade group.
Bethwaite
P
P
Department of Pathology, Wellington School of Medicine, New Zealand. pathpb@wnmeds.ac.nz
Smith
N
N
Delahunt
B
B
Kenwright
D
D
D001943:Breast Neoplasms / Q000145:classification* / Q000473:pathology; D002278:Carcinoma in Situ / Q000145:classification* / Q000473:pathology; D018270:Carcinoma, Ductal, Breast / Q000145:classification* / Q000473:pathology; D005260:Female; D006801:Humans; D009336:Necrosis; D015588:Observer Variation