Simplification of grading papillary urothelial neoplasia using a reduced set of diagnostic features.

Objective: To determine whether a reduced set of the histopathologic features used in internationally accepted classifications is capable of accurately grading papillary urothelial neoplasms (PUN).

Study Design: All surgical specimens from urinary bladders received during a 2-year period were reexamined by an expert uropathologist for assessing the accuracy of original nonexpert PUN grading and staging. Thirteen histopathologic features entailing 32 attributes were evaluated with regard to prediction of expert grade. Patients were followed for 35-59 months (mean, 47).

Results: A total of 88 PUN specimens could be analyzed completely including follow-up specimens. Agreement between original and expert grade was 71% for low-grade and 87% for high-grade PUN, with overall kappa = 0.53. The histomorphologic features most predictive of expert grade were architectural disorder, variability of nuclear enlargement, and absence of umbrella cells. Neither individual histomorphologic attributes nor their combinations were as predictive of expert pathologist grade as original diagnoses.

Conclusion: Improvements in PUN grading and prognostication are not likely to be accomplished by only reducing the number of histomorphologic features currently recommended by the World Health Organization and International Society of Urological Pathology.