A case of urachal villous adenoma with high grade dysplasia focally bordering on adenocarcinoma in situ

The urachus, or the median umbilical ligament, is a vestigial structure of the allantois that connects the urinary bladder and the umbilicus. Urachal carcinoma, originally described by Hue and Jacquin in 1963, is a rare non-urothelial carcinoma. The incidence is estimated to account for 0.01% of all malignancies, 0.5% of all bladder tumors, and compose 20e40% of bladder adenocarcinomas. Most urachal cancer is associated with poor prognosis because of advanced stage at diagnosis.1 Urachal villous adenomas, which may coexist with in situ and invasive adenocarcinoma, is even more rare than urachal adenocarcinoma. Kato et al. found that there are fewer than 40 cases of villous adenomawith or without other types of carcinoma reported in the literature.2 It is hypothesized that there is a biological progression of villous adenoma to adenocarcinoma, but only one case has been reported thus far.3 We present a case of urachal villous adenoma with high-grade dysplasia focally bordering on adenocarcinoma in situ.