FGFR3 and in situ carcinoma: Due to their inverse distributions as a function of stage and grade and the small number of double-mutated tumours (FGFR3 mutated, TP53 mutated) observed in small series, FGFR3 and TP53 mutations had been reported to be mutually exclusive events, with FGFR3 mutation strongly associated with the Ta pathway and TP53 mutation strongly associated with the CIS pathway [10], [11].