Histologically, the fronds of papillary tumors have thin connective tissue cores covered by transitional epithelium showing various grades of cytologic and architectural abnormalities. TCC is arbitrarily graded on a scale of I-III based on the degree of cytologic and architectural abnormalities. Papillary transitional cell carcinoma grade I. Papillary frond covered by epithelial layer of normal thickness on one side and a much thickened layer on the other. May be papillary or non-papillary with moderate loss of architecture and moderate nuclear pleomorphism. Note the greater degree of pleomorphism.
Tumors show marked cellular pleomorphism and architectural abnormalities and most are non-papillary.
The neoplastic cells may be barely recognizable as transitional. Note greater degree of nuclear pleomorphism and presence of prominent nucleoli. As would be expected grade correlates with invasiveness. Non-papillary tumors are usually high grade and invade extensively and deeply into the bladder wall. The pathologic stage of transitional cell carcinoma is a better prognostic indicator than the histologic grade.