Histological parameters and pitfalls in the interpretation of bladder biopsies in bacillus Calmette-Guerin treatment of superficial bladder cancer.

We report the morphological effects of intravesical bacillus Calmette-Guerin therapy on early post-treatment biopsies of the bladder in 39 patients with superficial transitional cell carcinoma (stage Ta, T1 or Tis) of the bladder. Although submucosal granulomatous inflammation in bladder biopsies of patients receiving intravesical bacillus Calmette-Guerin treatment has been described previously, a complete morphological description of the early effects of bacillus Calmette-Guerin on all bladder layers and the prostatic urethra has not been reported. In the majority of cases the superficial epithelium was eroded and the edematous submucosa contained noncaseating granulomas with a surrounding lymphoplasmocytic and eosinophilic infiltrate. Langhans' giant cells occasionally were found, and acid-fast bacilli were demonstrated only rarely by special stains in the 6-week post-treatment biopsy. In some cases the prostatic urethra and muscle bundles contained noncaseating granulomas. Features distinguishing epithelial atypia resulting from bacillus Calmette-Guerin treatment and superficial cancer include the presence of epithelial maturation, preserved nuclear/cytoplasmic ratio, smooth nuclear contours and lack of nuclear pleomorphism, nucleoli or cytomegaly.