Mesenchymal tumors

Abstract

Mesenchymal tumors of the urinary bladder sometimes pose a challenge to pathologists and have the potential to be misdiagnosed. These tumors are rare, thought to comprise less than 1% of all bladder tumors. A number of mesenchymal tumors are reported in the literature as single case reports or a small series of cases, which makes it difficult to accurately estimate their true incidence. Reports of sarcomas before the advent of newer immunohistochemical antibodies raise the question of whether some of these are true primary sarcomas of the urinary bladder or sarcomatoid carcinomas misdiagnosed as sarcoma. There are various types of stromal cells within the urinary bladder wall that are the precursors of these benign and malignant tumors. In addition, there are "tumor-like lesions," such as the postoperative spindle cell nodule, which on cystoscopy are also visualized as a mass. In this chapter, we briefly describe the most common benign and malignant tumors and tumor-like lesions of the urinary bladder.