An unusual case of bladder urothelial carcinoma that showed areas of adamantinoid (ameloblastoma-like) morphology is described. The tumor occurred in 69-ys-old patient. It was a recurrence of non-invasive low-grade urothelial carcinoma which had been resected 3 years ago. Currently, two transurethral resections were performed (to ensure the tumor removal was complete). The tissue from both resections contained urothelial carcinoma without invasion in lamina propria. Histologically, besides of conventional morphology of low- and high-grade papillary urothelial carcinoma, numerous foci of the tumor showed inverted growth with ameloblastoma-like features such as reversed polarization of basal cells and loose network-like arrangement of the cells in the lobules. At present, the patient is well one month after the resection, and he will receive intravesical BCG treatment. We suppose that adamantinoid (ameloblastoma-like) urothelial carcinoma can be regarded as a variant of inverted urothelial carcinoma.

Keywords: urothelial carcinoma, urinary bladder, transurethral resection, ameloblastoma, adamantinoid