Whorled Urothelial Cell Carcinoma: A Neglected Variant.

Twelve cases of urothelial cell papillary carcinoma with a whorled pattern of growth are described. This variant is reported with clinicopathological correlations and immunohistochemical findings. All cases showed this peculiar and distinctive curlicue histological pattern, ranging from 50% to 100% of the neoplastic population.