Small Cell Carcinoma Of The Urinary Bladder: Morphology, Histogenesis, Diagnosis, Immunohistochemical Markers And Therapeutic Strategies; Case Report And Review Of The Literature

Small cell carcinoma of the urinary bladder is a rare malignancy, comprising less than 1% of urinary bladder carcinomas. It is highly aggressive, with a dismal prognosis, usually presenting with advanced-stage disease. There is a male prevalence and the most common symptom is hematuria. Morphologically, this tumor resembles its pulmonary counterpart. There are many theories about the histogenesis of this tumor: urothelial, neuroendocrine and from stem cells.The aim of this chapter is to present our experience in the case of a 44-year-old man with a history of smoking (10 cigarettes/day), hospitalized for one month with intermittent hematuria in January 2007 at the Department of Urology, Prof. Dr. Th. Burghele Hospital, Bucharest, Romania. Ultrasonography and cistoscopy revealed a sessile mass, sized 37/30 mm. The tumor was removed by transurethral resection and the fragments were processed by standard histopathological methods: fixed in 10% formaldehyde, paraffin embedded and stained with HE and VG. We also performed immunohistochemical tests including Cromo, EMA, NSE, CD56, NK1, P53 and beta HCG. Follow up studies of the patient were conducted for 20 months. Echographic, CT, cistoscopic examination and a new TUR revealed no tumor relapse and no metastases.Histopathological examination showed a tumor proliferation composed mainly of sheets of small cells, uniform and rounded, mitotically active and a component of a typical low-grade urothelial carcinoma. Immunohistochemical markers emphasized that a diffuse positive staining of the small cell component for Cromo, EMA, NSE, CD56, NK1 and P53 was strongly positive (80%) and the urothelial carcinoma component was focally positive for beta HCG.The microscopical diagnosis was small cell carcinoma of urinary bladder coexisting with a low-grade papillary urothelial carcinoma, invading the lamina propria (pT(1)).The aggressive behaviour of this entity is due to the presence of the small cell component and possibly to the association with beta HCG positive immunoreactivity. Our patient was treated by local instillation with farmarubicine and six series of intravenous cisplatin. We mention that until now there is no agreement about a standard therapy management. Some authors recommend only cistectomy, while others, a combined therapy: cistectomy, chemotherapy and radiotherapy. Based on this case and data from the literature, we consider that immunohistochemical profile is helpful in diagnosis, and this type of cancer must be known not only by pathologist, but also by the urologist and oncologist because of its aggressive behavior and its different therapeutic strategies.