Myofibroblasts reaction in urothelial carcinomas.

The myofibroblast is a connective tissue cell with intermediate features between the fibroblast and the smooth muscle cell and unknown origin, which normally is present in only a few organs, but with increased incidence in malignancies. The patterns of myofibroblastic reaction may be synchronous, metachronous and mixed. The presence of the myofibroblasts has been demonstrated into the stroma of breast carcinomas, particularly in firm, retracted tumors with no inflammatory infiltrate. The present literature lacks data regarding the presence and the behavior of the myofibroblasts in urothelial carcinomas. Fifty-nine urothelial carcinoma specimens from patients admitted into the Urology Clinic of the Emergency County Hospital of Timisoara between 1999 and 2004 were stained with usual HE stain for the morphological diagnosis and immunohistochemically stained with smooth muscle actin, vimentin, and desmin for the detection of myofibroblasts. In biopsies sampled from normal urinary bladder and in urothelial carcinomas of the superior urinary tract Ta, we have not noticed any cells with myofibroblast morphology or immunophenotype. In Ta tumors, no matter the differentiation grade, we have not noticed myofibroblasts neither between the tumor cells nor at distance. The myofibroblasts were identified in seven of the 26 (26.92%) tumors in T1 stage. In T2 and T3 stage tumors the number of myofibroblasts differs from case to case, being significantly higher in tumors with high differentiation grade, G3.