Cytokeratin expression patterns in metastatic transitional cell carcinoma of the urinary tract. An immunohistochemical study comparing local tumor and autologous metastases.

The cytokeratin (CK) expression patterns of local, ie, primary or recurrent, high-grade-malignant transitional cell carcinomas (TCCs) of the human urinary tract and autologous lymphogenic and hematogenic metastases (n = 33) were compared. Special attention was paid to CK expression in the tumor invasion front and other areas where tumor-stroma interaction occurred to visualize cell populations with a metastatic phenotype. For this purpose, polypeptide-specific monoclonal antibodies to CKs 4, 7, 8, 10, 13, 14, 16, 17, 18, and 19 were used, employing the immunoperoxidase method. Results show that: 1) An increased expression of CK8 and CK18 is seen in the TCC tumor cells at the interface with peritumoral stroma in the tumor invasion front and with intratumoral stroma ('interface phenomenon'). Other than reflecting a quantitative change, this phenomenon might be explained by unmasking of CK8 and CK18 epitopes occurring in these regions. 2) Although in general the expression of CK13 in local TCC is decreased with increase of histopathologic parameters for progression, ie, grade and stage, an extensive proportion of CK13-positive tumor cells still can be found in some TCCs, even in metastases. 3) Morphologically recognizable types of aberrant differentiation in TCC, i.e., pseudosarcomatous or squamous differentiation and marked loss of differentiation, show altered expression of many of the CKs studied.