[Inverted papillary carcinoma].

Some authors consider the papilloma to be a very low grade papillary carcinoma limited to the urothelium. Similarly, inverted papilloma can be interpreted to be a papillary carcinoma with an inverted growth pattern. Furthermore, the association of transitional cell carcinoma and inverted papilloma supports this concept. We investigated the frequency of transitional cell carcinoma associated with inverted growth--synchronous or metachronous--in our setting. Our results show that this association is present in 1.7% of the pure transitional cell carcinomas and in 2.6% of the superficial pure transitional cell carcinomas (pTa/pT1). We underscore the possibility of misinterpreting these lesions to be benign, while in fact they are potentially aggressive.