To the best of our knowledge papillary adenocarcinoma in situ of the bladder has not been reported previously. We describe a case of transitional cell carcinoma in situ of the bladder associated with papillary adenocarcinoma in situ. While it is believed that most nonurachal adenocarcinomas of the bladder originate within cystitis glandularis, such transition is difficult to document. We assume that severe dysplasia of a papillary adenomatous component adjacent to papillary adenocarcinoma in situ represents an intermediate morphological change between cystitis glandularis and adenocarcinoma. Electron microscopic evaluation of glandular epithelium indicates that it represents the process of aberrant differentiation rather than a metaplastic phenomenon.