Value of immunohistochemical laminin staining in transitional cell carcinoma of human bladder

A prospective immunohistochemical study of 66 human bladder biopsies with and without transitional cell carcinoma (TCC) of the bladder was performed to assess the diagnostic and prognostic value of laminin staining in TCC of the human bladder. In all normal and nonmalignant inflammatory specimens, a continuous intact basement membrane (BM) laminin could be identified. In bladder cancer specimens laminin staining revealed focal interruption of the subepithelial BM with microinvasion in 2 of 6 specimens initially diagnosed as Tis(Pis) and 7 of 25 specimens initially diagnosed as pTa tumors. A statistically significant association between the pT category and BM interruption was found (p < 0.025). BM loss was directly proportional with the stage of the tumor. However, no significant association could be observed between BM interruption and the grade of the tumor (p > 0.25). In a short-term follow-up (mean 16 months) a statistically significant correlation (p = 0.01) could be observed between tumor recurrence and BM integrity in that a higher recurrence rate and shorter recurrence-free interval was found in patients with interrupted BM versus those with intact BM. Assessment of the vascular BM-staining pattern revealed interruption in specimens from 5 patients who died from advanced metastatic tumors. The metastatic process was found to be closely associated with focal interruption of the subendothelial BM (p < 0.001). From our results it appears that the adjunct use of immunohistochemical laminin staining in the histopathologic examination of TCC of the bladder is essential in more exact identification of the different pathologic stages and is also of help in the more detailed prediction of tumor behavior and prognosis.