Patterns of invasion and histological growth as prognostic indicators in urothelial carcinoma of the upper urinary tract.

The biological significance of squamous and glandular differentiation and different patterns of invasion in upper urinary tract urothelial carcinoma is unclear. We reviewed 268 cases of consecutive upper urinary tract carcinomas with respect to the presence of squamous and/or glandular differentiation and different patterns of invasion (nodular, trabecular, and infiltrative) and correlated data with patient outcome. Squamous or glandular differentiation occurred in 47/268 (18%) tumors and its presence correlated with high tumor stage (P<0.001) and grade (P<0.001). Invasive patterns were nodular in 49/227 (22%), trabecular in 95/227 (42%), and infiltrative in 83/227 (37%) tumors. The nodular pattern prevailed in low stage (P<0.001) and low-grade (P<0.001) tumors, whereas the infiltrative pattern prevailed in high stage (P<0.001) and high-grade (P<0.001) tumors. Multivariate analysis proved that tumor stage (P<0.001) and the infiltrative pattern (P<0.001) are independent predictors of metastasis-free survival, whereas tumor grade and squamous and glandular differentiation lacked independent influence on patient outcome. In conclusion, the infiltrative pattern of invasion significantly correlated with advanced disease and poor patient outcome. In contrast, the presence of squamous and/or glandular invasion did not prove independent influence on patient outcome. The pattern of invasion should be commented upon separately in the pathology report.