Normal anatomy and histology of the urinary bladder with pathologic correlates

Attention of the pathologist to basic urinary bladder anatomy and histology is essential to accurately diagnose bladder pathology, as well as determine TNM staging for proper prognostic evaluation. In this chapter, the normal anatomy, histology, and benign pathology of the urinary bladder are reviewed, with emphasis on key points that the surgical pathologist should know. Topics covered herein include bladder cancer staging according to the most recent AJCC Staging Manual, differentiating muscularis propria from hypertrophic muscularis mucosa, gross evaluation and handling of bladder tumors, functional anatomy, urachal remnants, diverticula, exstrophy, ectopic prostate tissue, intestinal and squamous metaplasia, von Brunn nests/cystitis cystica and glandularis, nephrogenic adenoma, polypoid cystitis, types of inflammatory cystitis, malakoplakia, fibroepithelial polyp, and Mullerian lesions. Potential mimickers of malignancy are noted, and characteristics used to differentiate mimickers from malignant lesions are discussed. This chapter is therefore a useful reading for genitourinary pathologists, general surgical pathologists who encounter bladder cases, and pathology trainees.