*3.3. Basaloid-Squamous Cells*

Basaloid-squamous cell carcinomas are aggressive neoplasms mainly located in the head and neck [46] and anal [47] regions. The tumor is extraordinarily uncommon in the urinary tract, with only a handful of single cases published to date [48–51]. Everywhere, most basaloid squamous cell carcinomas are associated with HPV infection [51].

Histologically, the tumor is deeply infiltrative and shows a typical biphasic pattern (Figure 2b). Basaloid atypical cells with high mitotic rate and scarce cytoplasm are arranged in lobes and nests showing peripheral palisading and stromal reaction. Basaloid nests are centered by squamous islands with evident keratinization. p16 is intensely positive in tumor cells.
