Pseudosarcomatous myofibroblastic proliferation of the bladder: report of 2 cases and literature review.

We report 2 cases of pseudosarcomatous myofibroblastic proliferations of the bladder unrelated to urological trauma. To our knowledge, these cases represent the longest followup (12 and 19 years, respectively) reported in the literature, which confirms the long-term benign nature of an entity that may be clinically and even pathologically mistaken as malignancy. A review of the literature revealed a female predominance (3:1), 50% of the cases manifested in the first 2 decades of life and mean age was significantly lower in male patients (p < 0.005). These facts suggest the existence of a hormonal factor in the pathogenesis of this entity. A predilection for fundus, and the posterior and lateral walls also is demonstrated. In light of the complex embryogenesis of the cloacal territory, it could be hypothesized that this lesion arises from embryonal mesenchymal remnants of the endodermally derived urinary tract.