Clinical and pathological characteristics of micropapillary transitional cell carcinoma: A highly aggressive variant

Purpose: We present preliminary clinical, histochemical and molecular findi ngs for 5 patients with micropapillary transitional cell carcinoma of the b ladder, a rare histological variant not widely recognized in the urological literature. Materials and Methods: The 5 patients were prospectively identified. In 3 c ases immunohistochemical staining for expression of CD31, p53, E-cadherin, and alpha, beta and gamma-catenin was performed on paraffin embedded tissue . Sequencing was used to identify point mutations in exons 5 to 9 of p53, a nd exons 1 and 2 of H-ras. Results: Of the patients 2 died within 1 year of presentation to our instit ution with rapid local extension along the bladder serosal surface and uret eral sheaths. Another patient; had progression to invasive disease within 2 2 months. In the 3 cases with immunohistochemical staining p53 was negative , despite positive staining of nonmicropapillary transitional cell carcinom a within the same specimen. Stains for the angiotrophic marker CD31 were ne gative. In all 3 cases normal membrane associated alpha, beta and gamma-cat enin expression was present. Examination of p53 sequences revealed a single point mutation in exon 8 of 1 case. In 2 cases different mutations in exon 1 of H-ras were noted. Conclusions: Micropapillary transitional cell carcinoma is a rare and highl y aggressive variant. Paradoxically, our study demonstrated no significant p53 abnormalities. The lacunar histological pattern did not appear to repre sent invasion of vascular spaces. Rather, these tumors seemed to have the a bility to disrupt and replace the normal stromal matrix to achieve rapid no nendothelial extension. Thus, micropapillary histology may predict a lesser likelihood of surgical cure.