Nest-like features in bladder, simulating the nested variant of urothelial carcinoma.

Nest-like structures are the cardinal lesion of different benign and malignant bladder entities. These entities emphasize the biological relevance of the subtle morphological nest plasticity. The authors present 25 benign and malignant neoplasms, sharing the presence of florid nest-like growth and the scarcity or absence of superficial papillary components. Differential diagnostic clues are discussed.

Cell discohesion and multifocality of carcinoma in situ of the bladder: new insight from the adhesion molecule profile (e-cadherin, Ep-CAM, and MUC1).

Urothelial cell carcinoma in situ (CIS) of the bladder is a superficially diffusive and highly discohesive disease. The authors analyzed the expression of some adhesion molecules (e-cadherin and Ep-CAM) and MUC1 in 32 unifocal and multifocal bladder urothelial cell CIS in an attempt to clarify this discohesion. E-cadherin was strongly expressed, in more than 75% of the cases. The presence of methylation of the CDH1 e-cadherin promoter gene was also investigated, but methylation was found in only one case. Ep-CAM was present in all the cases with a heterogeneous staining pattern. Similarly, MUC1/episialin was variously present in 94% of the cases without a polarized staining pattern and was expressed more strongly in cases with multifocal disease. Because loss of MUC1 polarization leads to interference with cell-cell adhesion mechanisms mediated by cadherins, these findings help explain why bladder urothelial cell CIS often shows a discohesive morphology and multifocality despite a strongly expressed adhesion molecule profile. Finally, Ep-CAM expression might provide some support for future target therapy trials.