Clinical significance of prominent retraction clefts in invasive urothelial carcinoma.

Micropapillary morphology in invasive urothelial carcinoma is an established predictor of aggressive disease. It is unknown, however, if prominent retraction is associated with more aggressive disease in the absence of classic micropapillary morphology. We reviewed a retrospective series of 309 radical cystectomy specimens with clinical follow-up data and documented the presence or absence of invasive urothelial carcinoma with prominent retraction clefts, defined as invasive carcinoma with retraction involving the majority of invasive tumor nests in at least one 100× field but without classic micropapillary morphology. Invasive carcinomas with plasmacytoid, sarcomatoid, nested, and small cell morphology were excluded, as were cases without lymph node sampling. In invasive conventional urothelial carcinoma, the presence of prominent retraction clefts was associated lymph node metastasis (odds ratio 4.7, P = .0015, Fisher exact test) but not pathologic tumor stage or several other oncologic parameters (all Ps > .10). Similarly, invasive urothelial carcinoma with micropapillary morphology had lymph node metastasis more frequently than conventional urothelial carcinoma without prominent retraction clefts (P < .001, Fisher exact test), but there was no difference in pathologic tumor stage or oncologic parameters (all Ps > .10). There was no statistically significant difference in rates of lymph node metastasis between invasive urothelial carcinoma with micropapillary morphology and conventional urothelial carcinoma with prominent retraction clefts (P = .54, Fisher exact test). The findings suggest that prominent retraction in invasive urothelial carcinoma may be associated with more aggressive disease, even in the absence of classic micropapillary morphology.